Tiberian Fiend

The automatic in my '67 Cutlass only shifts manually by shifting from low to drive. Is there an easy way to fix this, or is this a job for a transmission shop?

edzolz

The best way to fix this problem is to get rid of the two speed and replace it with a TurboHydro 350. Bolt in replacement.

JohnnyBs68S

Sounds like either a vacuum leak or the modulator is shot, leading to the trans thinking the engine is WOT and not shifting when in D. I'd check the vacuum lines between the intake and modulator, and checking if the modulator will hold a vacuum. If not, I think the modulator can be replaced without dropping the trans.

TripDeuces

Or you just have a vacuum leak.

Tiberian Fiend

I probably do have a vacuum leak since I broke some of the tubules that control the A/C, but I was experiencing the problem before that. Is this what I'm looking for? https://www.ebay.com/itm/GM-Pontiac-...t/111482538193

JohnnyBs68S

That looks like it. I'd check your old one first to see if it really needs to be replaced. If it isn't getting sufficient vacuum due to a leak elsewhere upstream, you'd get the same symptoms.