i got a 1977 k10 with a 6.2 and 350th that was said to be bad. i got it to start and run well but when i shift it in to gear it wouldnt move. so i got another 350th that was said to work but when i got it put in and started it it wouldnt shift past reverse. and even in reverse it wouldnt move. im a 19 with no money and 2 350th.n what do i do? help is much apprseated.

 

When you say you can't shift it past reverse do you mean the shift lever physically won't move. If this is the case then you probably just didn't set and sync the linkage and shift lever properly when you installed the tranny. Probably the tranny was already in 2nd gear or got moved in installation, and then tightened everything up wrong. If this is the case you need to make sure the tranny is in park, as well as the truck.

Other then that, (and I am not trying to insult you here). Did you get the torque converter/flexplate bolts in, checked the fluid level.

If this doesn't apply I think I need a better understanding of what is happening

 

i did sync the shifter link to park, (i think), and the torque converter is for 350 engine and 350th but i had a 350th that would shift through all the gears but not catch. only park worked and all the other gear were like netrual. but the 350 in there will shift in gear if i get under the truck and shift it by hand after messing with it.

 

Double check your sync.

Also you need a Diesel torque converter, I believe. A gasser torque converter won't work. Or, at least, it won't work well.