ok, after a 40 minute cruise at 70 mph, as i was slowing on the ramp i noticed my speedo dropping in increments instead of smoothly. a few minutes later, after starting from a redlight, there was a strong "clunk" from the trans around the 1-2 or 2-3 gear change (auto 4l80e, 2500 Burb with 8.1 4x4, 83000 on the clock). trans temp was good, and remained good for next hour of driving at about 60 mph for most of it. fluid is good too. on the trip back home i did hear another clunk from the trans- seemed to be when i let off a bit after a moderate acceleration- again around the 2-3 shift point. had the family with me so i made sure to go easy on the throttle because i wanted to make it home. i haven't had a chance to get out and try to reproduce the clunk or see more clearly when/if it is happening all the time. one other thing, my push button 4wd has not worked for a month or so- i think it is the transfer case control module, and the dealership couldn't communicate with it to update the software. haven't had a chance to verofy grounds to it.

on the speedo, it decelerates at a very jumpy pace and still shows 5-10 when you stop for a second. when you start, it jumps to 10-15 very quickly.

maybe the trans noise is totally seperate, seems like the speedo is the stepper motor maybe. or could the two things be tied together? any thoughts/suggestions/help is appreciated.

 

The speedo is most likely the stepper motor and not related to anything in the transmission.

If the issue is something other than the cluster and the truck is thinking its going different speeds than it is then it could probably make it shift funny.

 

yeah, decided the two are not connected.

but, is it possible my "clunk"- which i can't reproduce regularly, could be torque converter having issues? noticed today while decelerating at about 40-50 mph off throttle it did it. does the 4l80 converter lock/unlock or ever go bad? maybe dumb question, just don't know much bout transmission issues.