[joemud]

I have a 1985 Chevy Silverado that I just bought and has a TH350 transmission instead of the TH400 that is suppose to be in it. Does anyone possibly know why my TH350 transmission keeps downshifting from drive to 2nd? The fluid is good, installed a new filter and gasket, replaced the vacuum modulator and has good vacuum. All the linkages are good, no binding. HELP!!!!

Joe​

 

[Revredneck]

Is your kickdown (detent) cable properly adjusted? Are you sure you've got good MANIFOLD vacuum, taken off the manifold and not off the base of the carburetor? When exactly does it shift down?
Good Luck and God Bless

 

[2COR517]

Does it downshift under normal cruise, or when you start to get on it? Do you happen to know what gears it has? And tire size?