I'am in the process of changing my 1969 Chevelle over from a powerglide to a turbo 350, The cooling lines to the radiator on the powerglide are small lines, the fittings that go into the turbo 350 are bigger than the powerglide ones, can a smaller brass fitting be used in the trans? The reason I asked is because what would be done at the radiator end of the lines. I plan on buying new lines for the turbo 350 but want to know about the line size since the fittings for the radiator has to be the same size as the trans. end. Thanx Jerry
It seems to go from one thing to the next on this project and my patience is starting to run out on this job.:mad::mad::mad:

I would think that if GM thought the larger 5/16 od lines weren't needed, they wouldn't have used them.

I would buy new lines, not use smaller ones myself.

(I'm assuming the old PG lines are 1/4"od :confused: )

If bigger lines are used what about the size of the fitting that goes into the radiator. Something is going to have to be changed and I hope it doesn't have to be the radiator. Why would there be small lines on a powerglide and larger lines on a turbo 350?

I changed my '69 Malibu from PG to TH350 and the PG lines attached to the TH350 fittings fine. It was originally a 307 Malibu if that makes a difference (I doubt it). I had to do some bending on the lines at the trans end but they worked. I believe myTH350 came from a Monte Carlo. Maybe yours came from a truck or something that used larger lines.

Hmm, seems odd that the lines on your 69 would be smaller than the ones on Von's 69.
See which size open end wrench fits the line - 1/4" - 5/16" or 3/8"

I'm guessing the TH350 he has is from an Impala or truck or something with bigger cooling lines than a '69 Chevelle with PG or TH350. Probably just needs to change the brass inlet/outlet fittings on the trans.

Sounds like your TH350 is missing the brass fittings that screw in the case. Just swipe them from the PG. All TH350 used these brass fittings in OEM install, and lines should be 5/16" on both PG and TH350.