olds 307 and 403

The original TH350 is a dual pattern for my 70S. I picked up a dual pattern TH350C from a 86 Caprice. My understanding is the TH350C dual pattern is more rare than the non lock up trans, which seems backwards considering the time's Coporate engine strategy. I know from experience many TH2004R's are dual pattern, which makes a lot more sense. Why GM didn't just make dual or one pattern is also stupid to begin with.

Sugar Bear

I don't know how common the dual pattern is but...look at the trans to confirm it is not a TH250C. They look very similar to a 350 and were used in that era. The 250 will have an external band adjustment bolt on the right side somewhere around the detent cable...been there.

Good luck!!!

olds 307 and 403

Me too, I fried a good high mileage TH250C in a hurry behind a 403, lost first gear, first time out. That is when I learned about the dreaded stud. So this is a TH350C, a Transgo shift kit and a 2500 stall Hughes lock up converter will be going in along with a pan with a drain plug.

cherokeepeople

my old powerglide had a drain plug.why GM decided to get rid of it always made me wonder.but on my 2002 suburban it has a drain plug so somewhere along the line the be otchin must have convinced em to put it back in.i also wish they would have put a drain plug in the converter like ford and dodge.

olds 307 and 403

My 70 trans has a drain plug in the converter, couldn't get it out.

VI Cutty

Volkswagen did away with the drain plug in the bottom plate of the old Beetle air cooled engines in the mid '70s. The philosophy there was that people were shortcutting on maintenance, draining/replacing the oil but not removing the plate to clean and inspect the oil screen which was the only filtration on the engine.


Maybe GM's motivation was something similar?

olds 307 and 403

That makes sense, so it is probably something else totally different.