I'm going to be putting in a new torque converter myself and I have heard that screwing threaded dowels into the engine block to guide the trans in place is the easiest way. The dowels need to be the same bolt size as the transmission bolts- what size is that??? And of course how long should these dowels be?

While on the subject, the car I'm doing this on is a G-body- v8/TH-2004R. I really don't want to take the whole trans out if i can avoid it. If I pull the trans back, how far back should I take it to swap converters? Thanks alot

 

It has to go quite a ways back to swap converters, probably 6" at least.

The bell housing bolt size is 3/8"-16

 

Your tunnel is only an inch or so behind the bellhousing, so
dropping the tranny is mandatory. Make one of your dowels
a couple of inches longer than the other one. That way you won't have to start both dowels at the same time.