Does the ironglide need dowels in between the trans and adapter.? I can't find any detail or pics with them. It would be a stepped dowel 0.625" x 0.400" approx.
I don't remember, it's been too long. But seems to me that the recess in the large opening, aligns the transmission to the adapter.
I'm with Jim. I posted earlier but took it down. I had said they were not needed but looking at your photo's I couldn't say 100% that machined step cut's were all that's needed. I also do not remember (may have forgot) pins being there. To take a guess GM probably realized they over engineered the need to have pins when adapter index's to trans as is and deleted them soon after.
Is it possible they are fixture holes for machining like the ones front and back of pan rail (fuel pump side) on this block?
I think there are two holes the are counterbored and some had a short hollow dowel, or heavy tubing, that aligned the holes and a normal bolt passed through them. But I haven't worked on an iron glide since the 70s and it is a faint memory.
I have two CI Powerglides on the shelf, one has a broken case in the bell housing area, and the other is complete with the mid plate separated from the trans. I looked at both and neither trans or the mid plate have dowels in them. I just kinda looked at them, but I think the ones I have, don't have the larger size lower holes. I can look at them better tomorrow, and post a photo if you like. Bill
The dowel holes do line up with a loose fitting 3/8'' bolt, in fact the 5/16" bolt holes that secure the trans to adapter have alot of clearance too. So it must be the casted in ring or counterbore that keeps the two from drifting. This trans was from a 1950's 235 six. But this has been behind a 348 in a '60 Impala for about 20 years now.
I don't think so....the 6 cylinder versions have an "ear" on the bellhousing, where the starter fits. They don't swap.
Yep, your right _two different castings To get this trans rebuilt, the owner supplied the buider with a six banger version to replace front and rear pumps and some other parts