2005 engine / trans swap from 1500 to 2500

[Branczdad]

I have two 2005 trucks, a 1500, 5.7 auto, and a 2500 , also 5.7 auto with a blown up motor.I just purchased the 1500 with the intention to use the motor in the 2500. One factor that caused the 2500 to blow up was a severe downshift caused by the PCM, at highway speeds, or so I was told by the previous owner. The blown up truck has 340k miles on it. The running truck has 211k miles on it. Blown up truck has a recent Jasper trans put in it. Both trucks are 4 wheel drive. Are the transmissions and transfer cases similar enough that I can swap them, or idles the bigger truck have beefier internals in the transfer case ? Also wondering how similar the PCM would be between the two, just in case it was the culprit behind this blow up.

 

[ST-8]

He probably never got got quick learn done after the trans was put in an had the problems he was mentioning. The trans are the same (545rfe) but idk about the transfer case between the two.

 

[Branczdad]

He had driven the truck for a while with the rebuilt trans in it. An experienced SAE Master Mechanic told me that if the engine starts to have big problems, that the computer will drop it into low gear, regardless of the speed. I believe this to be what happened here. What I don’t know is what damage this may have done to the trans internally