Turbo 350 no 3rd gear?

[PRattenbury]

I have a feeling I'm not gonna like the answer I get, but here goes. I've never driven my 80 short bed fleet side anywhere since I've owned it, except around the block a couple times. I finally gave up on the Pypes exhaust and decided I had to go to custom exhaust shop to get the exhaust finalized. Anyway, it was the first time the truck had gone anywhere. The exhaust shop is 15 miles away. I had the truck parked with the nose facing up hill in my driveway, which caused a massive tranny fluid leak. No big deal, I think. I put the truck on level ground on the road in front of my house. I check the fluid. Truck won't move in any gear. I put 2 quarts of tranny fluid in it, and the truck goes into gear. Cool. I take it around the block,and I have all the gears. Off I go to the exhaust shop. Five miles down the road the truck jumps out of third gear. I still have second. So I stop at a gas station and check the fluid again. It's low. I buy 2 more quarts of tranny fluid. It takes 1 1/2 quarts and it's full. Off I go again, with all the gears. 9 miles later, I lose 3rd gear AGAIN! I limp it to the exhaust shop and get that done. Get back in the truck, I have all the gears again. I get back on the highway headed home. 10miles later, no third. I have to stop at the parts store. Did my business, check the oil and tranny fluid. All looks good. Get back on the road, no third gear. Run it home in second. Go to back in to the driveway so I don't leak, reverse seems to slip. I'm gonna check the fluid once again. And I'm gonna check the vacuum/modulator situation. But something tells me I have a dead tranny. Anything else I might check before I declare it a goner?

[PRattenbury]

I inspected the vacuum line between the manifold and the modulator valve. It is connected and seems to be in good enough condition. I have a steady 19 inches vacuum on the gauge. It's not looking good for the home team.

[ont_guy_38]

Might be the governor one the side of the tranny is sticking , you don't lose much fluid when you take it out , might be worth checking it out