Lockheed C-130B Hercules, N117TG c/n 3018.
IAR moved to Coolidge,AZ with DC8Fs, out of airtanker industry.
And indeed, this Herc looks operational but has no airtanker identification number. It used to carry '31'.

The day of my visit was a sunday and the offices were abandoned, no one around whom I could ask any questions.

Here is the history from Lars Olausson's Hercules Production List:
USAF units: Jul57 61TCS - 1962 18TCS - Aug64 314TCW - May67 4442 CCTW - Nov69 433 TAW ER. To S.Vietnam AF Nov71 and returned to USAF - 327TAS Jan76, Jul76 - Oct77 143 TAS - Dec79, 1981 105 TAS - Apr81, Jan88, last C-130 modified from 'Roman nose', Jun89.
Reg'd N117TG to T&G Aviation, Oct89 (Apr90 white top, Mar91 first civilan aircraft to arrive in Kuwait), Jun92 converted to waterbomber, Jun93 to Securit Civilé France ('81'), participated in test for passive noise suppression, Feb99 leased to RE/Max Ballooning Company, Mar2000 stored at Chandler, Jun02 reg'd to Int'l Air Response, Sep02 operating for the Spanish governement...
[Lockheed Hercules Production List 1954 - 2004, by Lars Olausson]

International Air Response was previously named T & G Aviation.
The company started aerial firefighting operations using 2 leased Douglas DC-7B's. These 'borate bombers' were leased from Arizona-based Airtankers Inc. in 1975. N51701 and N4887C were contracted by the US Forest Service and became based at Wenatchee,WA.
T & G stood for the names of the 2 founders: Sergio Tomassoni and William 'Woody' Grantham. Initially, the company was formed at Buckeye,AZ.
A few years after T&G's formation, a 50 percent share in Airtankers Inc. was bought and in 1979 followed a complete takeover. During 1978 T&G had moved to Chandler Memorial Airport, on the Gila River indian Reservation.
For a long time the Douglas DC-7 was its main type of aircraft and it is great to see N4887C still present here in obvious splendid condition. Bob Wofforth, former Air America pilot, was chief pilot in the early days and also flew N4887C.
Around the early-1980s T&G received a permit to operate adhoc cargo contracts, which included the fish-hauling contracts in Alaska.
The above details were learned from a 1981 copy of Propliner magazine (Vol.11), article written by Stephen Piercey.

Aad van der Voet added: "T&G was formed in 1973, and operated out of Chandler-Memorial Airport. In 1997 they were reorganised as International Air Response Inc. and moved to Coolidge,AZ a short time later. No connection to Gene Packard's former Air Response at Mesa's Falcon Field."

These days, I was told, IAR manages to keep itself in business by "..mostly military suppport ops, para training and even some missile testing."

UPDATE DEC.2014: " IAR has essentially moved their operation to Phoenix-Mesa Gateway Airport in Mesa. They still have a facility at Coolidge, but the active aircraft are based at Gateway.
Still at Coolidge are three C-130 hulks and the DC-7.
The C-130s still present are 56-530, 56-534, and 57-482.
57-520, which was previously at Coolidge, was restored to flight status in 2012 as N119TG.
And 57-482 still carries an active registration as N133HP." -Chris Kennedy

And: "As well as the 3 Herk hulks, there is (or at least was in October) the cockpit of a 4th one.
This appears to me to be from 58-0729 (nose previously reported at Williams/Gateway)."
Mike

What a fantastic building!

Airport History:
The Coolidge Municipal Airport was originally constructed in the early 1940’s by the U.S. Dept of the Army.  Originally constructed as an air transport command base, Coolidge Army Airfield served as an auxiliary operating base for Williams Field during WWII. 
The original airfield was constructed with 3 runways in a triangular configuration.
Of these 3 runways, two remain: Runway 17-35 and Runway 5-23. 
Numerous support facilities were constructed, of which a 120-foot by 80-foot hangar still remains.  On 19Jan1950 the airfield was transferred to Pinal County since the airfield was no longer needed by the U.S. Dept of the Army.  Pinal County owned and operated the airport until 1959 when the City of Coolidge obtained ownership of the airport. 
On 02Mar59 the airport was officially transferred from Pinal County ownership to the City of Coolidge.
[Source: www.coolidgeaz.com]
The Council intended to tear it down, put up another Wal Mart or something, but I was informaed late Jan.2010: =COOLIDGE WILL KEEP HANGAR!=
'he city council voted last Monday night 25th and was unanimous in repairing the damage to the hangar and continue to maintain and support the hangar as a treasure for all of Arizona...'

See also www.airnav.com/airport/P08

Lockheed C-130A N138FF (c/n 3227) was supposed to be reregistered to N119TG on 05Nov07, but this hasn't been applied. So this aircraft has no operational status for the company, I suppose.

57-0520 (c/n 182-3227) RC-130A was degraded to C-130A in 1969. To Hemet Valley Flying Service as N138FF in 1998 for use as water bomber/chemical spray aircraft. [Source: Joe Baugher]

N138FF was reregistered as N119TG 11May2007 (manufactured 1957).

DC-7B (N4887C/Tanker 33) looking absolutely splendid in its partial Delta colourscheme.. Looking ready to go for another season, but did it get any contracts?
It sure was hot enough to be on fire alert, but during my visit the main fire fighting activity was in Northern California.
Update further below...
Nothing much changed I noted during MY 2017 REVISIT

UPDATE DEC.2014: "They made two attempts to fly the DC-7 to Gateway, back in May of this year.
The first time they had a fire in number three engine.
The second time they aborted a takeoff attempt during which they locked up the brakes and skidded almost to the end of the runway.
The brakes were destroyed, as were several tires.
As of December 6th it was still at Coolidge, awaiting brake parts." -Chris Kennedy

N4887C is looking at a less fortunate 'mate'... Update Oct.2017

UPDATE MAY 2019: The unbelievable happened, a new attempt to bring N4887C back in the air saw it taxi under own power on 08May2019!!!

Screendump of a video by Bill van Dyck shared by him on Facebook's 'Douglas Big Props'.

UPDATE NOV.2019: "N4887C was purchased by the Delta Flight Museum (website) and after a lengthy restoration at Coolidge,AZ (this DC-7 was often referred to as 'the Coolidge DC-7' for its extended stay here) it went airborne on 16Jun19 to ferry the vintage propliner home to Atlanta. Unfortunately, after take off serious technical gremlins appeared and N4887C diverted to nearby Phoenix–Mesa Gateway Airport (IATA: AZA; ICAO: KIWA).
When I checked FAA N-inquiry database I found it still reg'd to Int'l Air Response, since 03Jun80.
The engine troubles were adressed and 'Ship 717' made the last leg 'home' on 16Nov19.

The famous 'African Queen' has been broken up and was transported from Chandler,AZ to Coolidge at some point.
This is DC-7C 'Seven Seas' once operated as G-AOIF by British BOAC.
N90804 (c/n 45116/750) on AIRLINERS.NET
Visit my 2017 report, which includes a revisit to Coolidge Airport and Mesa's Falcon Field (a.o.). Plus a 2020 update of DC-7 'African Queen'!

In May 2013 it was seen lying on the ground at Mesa-Falcon Field; see also Bob Reid's images of DC-4 N67016 being scrapped on Photos by Friends & Guests (37)

The website of Int'Air Response, www.internationalairresponse.com quotes the use of 6 Lockheed C-130 Hercules aircraft. Here present were N138FF (supposedly reregistered as N119TG), N131HP, N131FF (supposedly reregistered as N125TG), N117TG, N118TG & N121TG. So all accounted for.
JP Airline Fleets 2007 only lists N117TG and N118TG.
JP Airline Fleets 2007 also lists, besides DC-7B N4887C, 2 Douglas DC-8 aircraft: N995CF & N797AL, both for sale or for lease,ex/ Emery aircraft.
The above website states: "At International Air Response we operate three of these aircraft, two DC-8-63s and one DC-8-62." Probably not based here at Coolidge. 
From the above, and the lack of airtanker numbers on N117TG and N118TG, I would say only DC-7B N4887C is used for aerial firefighting..?

C-130A N131FF (c/n 3138, ex/ 56-0530 USAF) carried airtanker identification '81' also for Aero Firefighting of which I don't know much, except it was listed as having its headquarters at Anaheim,CA though Tanker 81 seems to have lived mostly at Chandler,AZ.

Nathan Addison wrote me in July 2009:
"I was delighted to see the Hemet-Valley Flying Service C-130s I grew up around as a kid on your website.
They, Hemet-Valley Flying Service, obtained five C-130A aircraft from the US Government to use as air tankers in 1988; they were quickly converted and began use, with two flying in 1989. All were based at Hemet with N138FF and N131FF among them. They were Tanker 81, 82, 83 and 88.
Of those four, all were painted with the exeption of 83, which was quickly prepped for use and was never completely painted to match the others. Instead, Tanker 83 flew in its original olive drab USAF colours with a large orange stripe on the tail that had 83 in the center, and '83' painted just below and behind the cockpit.
A fifth was cannibalized for parts and was only recently removed from Hemet-Ryan in 2008 after sitting there for over a decade.
Tanker 82 (N135FF) was tragically lost in a mid-air explosion and wing seperation in August 1994. An eerie event, foreshadowing of what would happen to the Hawkins & Powers C-130 eight years later...
I think a lot of the registration confusion on some of the aircraft were that they were re-registered to a leasing company after they were obtained... probably the Anaheim hit you got. The strange thing is registration was handed off several times as far as I can tell, but they always remained in the hands of Hemet-Valley Flying Service."

Recommended reading for individual histories on Lockheed Hercules aircraft are the reference guides written by Lars Olausson.
Lars Olausson is a retired officer of the Swedish Air Force, who has published an annual volume on the history of the Lockheed C-130 Hercules airlifter, titled the 'Lockheed Hercules Production List'. Issue 1954-2009, the 26 edition, has been printed April 2008!
[Source: Wikipedia]

Another source of reference is www.c-130.net

Here is an update sent by Nigel Hitchman dated 05mar2014:

"I went to Coolidge,AZ last weekend and found people working on the DC-7: the no 1 and 2 engines had been run for the first time in several years the week before and now plugs were being changed and other maintenance done; engines 3 and 4 were due to be run shortly.
Apparently the plan is to fly the aircraft to Mesa-Williams Gateway, where International Air Response have a hangar and there further restoration work will be done.
It is not in airtanker configuration any more, the tanks have been removed, but maybe they are easy to re-install.

UPDATE Dec.2014:
"IAR has essentially moved their operation to Phoenix-Mesa Gateway Airport in Mesa. They still have the facility at Coolidge but the active aircraft are based at Gateway.
Still at Coolidge are three C-130 hulks and the DC-7.
The C-130s still there are 56-530, 56-534, and 57-482.
57-482 still carries an active registration as N133HP.
57-520, which was previously at Coolidge, was restored to flight status in 2012, as N119TG. "
-Chris Kennedy (below are three images he sent)

Tanker 81, C-130 N131FF (ex/ 56-530) reg'd N125TG (reserved 19Mar14). '81' is its former US Forest tanker code.

Tanker 131, N131HP (ex/ 56-534), registration reserved for IAR 30Sep11 with renewal scheduled 11Sep14. But N126TG was also reserved (23May2014, Certificate reg'd 15Feb08). Academic probably.

Tanker 133, C-130 N133HP (ex/ 56-482), registered 07Mar07 for IAR.
I have N133HP in better days on my website: SCANS-ARCHIVE-PROPLINERS (#2) @Santa Barbara,CA (2000.)

Mike Bursell sent me this image (Dec.2014) as an update. This cockpit of an unidentified Lockheed C-130 Hercules is a recent addition here at Coolidge.
Mike wrote: "Taken 28Sept2014. I’m 99% certain that this is 58-0729.
Reasons are, firstly that it has clearly been stored in AMARC (58-0729 was there 19Mar01-12Jul00), second – you can read off the digits '07..' through the paint.
And, finally, because the nose of 58-0729 has been seen previously at nearby Williams/Mesa-Gateway.
Other candidates do not match these criteria."
It was still in place in march 2017, little or no change to it.

The Road Goes On... back to US Southwest 2008