With OD on the truck crises at about 2000 rpm at 72mph. When it drops down to about 1800 rpm and decides to downshift, it can't find a gear. I have to get out of the gas then on it hard to get it to downshift. Is this a sign that my tranny is going or a function of running nearly 33" tires with stock gears? It does have 207k miles on it and I have no idea if this is the orig tranny or not. It also shift hard when I start off and get out of the gas before it does an upshift.

 

If the tranny was replaced,maybe bands need adjustment

If not, and 207K, it may be on its last legs...hows the fluid?

 

how is the fluid level?
3.55 gears and 32.8" tires aren't the best combo compared to stock size tires. trust me, i know. 4.10's are soon to come for me.

 

I put 2qts in to bring it up to where it needed to be. It ran smoother for an afternoon and then back to rough.

 

are you leaking anywhere? and did you check it when hot and in neutral? the transmission doesn't pump fluid when it is in park.

 

It was hot and running in N sitting outside the auto parts store. Was barely reading on the stick when I got the truck. What scares me is that it just got done pulling a pontiac grand prix for 1000 miles.