I blew the transmission in my 2004 Silverado and replaced it with the transmission of a 2002 Silverado. it will go into 4wd no problem and drive just fine in 4wd, it has alot of trouble shifting into 2wd and then when it does i can drive normally for about 30 seconds then its just like it goes neutral, and if im in 2wd and try to put it in to park while it 2wd i get a had grind as if the truck is still moving when i put it in park. i dont even know where to start looking on this thing or what to check. it feels like the real drive shaft just isnt being engaged in 2wd.