The normal way to test at the dealer or any other qualified repair shop would be to hook up a professional scan tool an check for coolant temp sensor data input , also to see if the PCM/ECM - engine computer can control ( turn on ) the cooling fans . Also check for codes . Three relays that are controlled by the engine computer are what turn on the fans . Watch this video
https://www.youtube.com/watch?v=Qn6jLSyqYA4
4wd or 2? well the RPO tag tells you which tranny box is there, and matters. some cars have more than one transmission used, GM sure. 4L60E is common. 700 is useless code means tranny problems but 717 sure in turbine speed, and is on the tranny oil pump the turbin connect to the pump. 8 transmission use no counting the diesel so learn to read YOUR PRO codes. ALL GM cars /trucks all have RPO codes. (as builts) and will tell you in 1 second what M coded transmission is there Mxx but this this sensor is not easy reach. I will do just 1 the 4L60, have full manual on it. 2photos for you of ISS, (aka) Automatic Transmission - 2ML70 Automatic Transmission - 4L60-E/4L65-E/4L70-E Automatic Transmission - 6L45/6L50/6L80/6L90 Automatic Transmission - Allison id 249 IN this photo deeper, we see 250 ID.and the pump in your hands, or TC removed.TC does not fall out of cars, we yank the whole tranny back on a tranny jack tolleysorry not easy .
Rather than swapping out, why not get the one you have repaired and rebuilt? Doing swaps with other model years only works reliably a year either way because of changes in the electronics.
https://www.google.com/search?q=transmission+repair+near+me
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check and test the front sensors for damage and rust around the sensor port gm had problems with with rust getting under the sensor ring where it would bolt on to hub
The flasher looks nothing like the old flashers. It will be located behind the drivers side lower dash (under the steering wheel). It will be a small black box that is about 3 inches wide, 2 inches deep, and 1 inch thick. It may be somewhat difficult to locate because on some of the GM trucks they actually hide it behind the gauges but to the left of the gauges. in the link 1/2 way down shows location and descriptionhttps://www.gm-trucks.com/forums/topic/104429-where-is-the-turnflasher-relay-on-an-03-2500/
Plusieurs choses : 1- Pression d"essence
2- Systeme d,ignition feu aux bougies
3-Doit sortir les codes de defaillance avec un moniteur.
4-De l,eau dans l,essence
5-Mise au point (Bougies ,cap , rotor,nettoyer le trottle body, changer filtre a air, filtre a esscence.etc
Hope it helps.
Unless I am mistaken (and it is possible), you typically must have two (2) working original key fobs to program a third.
Is your original not working either? Any custom work to the vehicle recently?
IN this photo deeper, we see 250 ID.and the pump in your hands, or TC removed.TC does not fall out of cars, we yank the whole tranny back on a tranny jack tolleysorry not easy . 
