QuestionIs there a vacuum modulator on a 1978 Ford E350 Van with a V8/7.5 liter engine (460)?
If so where is it and can it be replaced?
AnswerI'm not signed up here to advise on trucks, especially a 1 ton truck, but I'll make a guess. Unfortunately, you didn't tell me which of the 5 available transmissions it has, so I'll answer for all of them, and hope I hit the target:
Eliminating the manual transmissions, there are 3 automatics;
All of the automatics (C4 Dual Range, C6 Dual Range, and the Borg Warner Cast Iron case Dual Range units) have a vacuum modulator, but they are all different, and you need to know exactly which transmission you have to order parts for it, so you will need to get under the truck and find the data plate, and copy down all the numbers off it. There are at least 10 different vacuum modulators for these transmissions, depending on vehicle application, engine, rear axle ratio etc. They all "look" the same but they are color coded with a paint stripe or band to identify which part number they are. Using the wrong one can cause rapid wear of the transmission, and poor shift quality.
As for where they are located, every one I've seen has been on the passenger side of the main case, toward the front of the case, and can be identified by the vacuum line that goes into it. Again, I've only worked on cars, so I can't tell you that big trucks are the same, but I would guess they are.
I hope this is helpful.
If you go to a NAPA store with the info on your trans case, they should be able to find you the right part.
Dick
