Th350 Converter Change Out

BigOrange · September 13, 2010

Hey Guys,

My old truck is '71 GMC 2wd with a TH350 auto trans in it. The trans is set up with a stage 2 shift kit and some other minor alterations but I'm going to change out the converter. The one that's currently installed has a stall just slightly above stock (listed @ 2400) but I'm going to a 3600 B+M holeshot converter since I have a big cam and need the higher stall for my set-up.

My main questions are as follows..........

1.) Has anyone swapped out the converter without completely removing the transmission???? Since all I really need is to get the 2400 out and the 3600 in, I was wondering if anyone has already tried (and failed/succeeded) to unbolt the trans from the cross member and engine, and lift/slide it back on the cross member enough to be able to remove the converter without completely pulling the trans out???? To me, it looks like there would be enough room that the trans could be slid back enough between the cross member and the cab to get the converter out.

2.) If question #1 is a NOT POSSIBLE, in order to drop the trans I have to get the cross member out of the way. The cab isn't coming off so whats the best suggested way of getting the trans down and out????? The stock cross member is 2 piece with the upper support being riveted to the top of the frame.

Can I undo the lower bolts on each side of the cross member connecting it to the frame, CUT the rivets (3 on each side) that attach it to each upper section, then flex the upper ones up slightly enough to remove the lower portion so that the trans can drop?????

----------OR, am I going to have a huge pain in the ass and have to pull the motor/trans together?

See Attached Pic for what I mean......

born-to-fish- · September 13, 2010

Why not remove the bolts on the upper xmbr as well? Then you can slide the xmbr back far enough, or rotate it to get it out of the way for the tailshaft.

It would probably be less of a pain to remove the trans. completely. You have to disconnect everything anyway. Be sure to support the engine though, usually a couple of pieces of wood at the back of the block wedged against the firewall should suffice. A long board with a couple of guys on the ends is the way I've done it before, that is if you don't have a tranny jack.

BigOrange · September 16, 2010

I'd like to remove the cross member all together but the problem lies in that there is little to NO room between the cab and the upper portion of the frame to remove the rivet. I could possibly shear it from underneath but I'm worried that I wouldn't be able to get bolts back in afterwards.

My main question would be the second part about removing the 3 rivets on each side of the lower portion to get the cross member out and leave the two upper supports in place? That seems like it should be relatively easy, yes???