Attention: TDR Forum Junkies 
Dp, thats cause most shop mechanics are dipsticks themselves.
Jb, I hate to be the pessimist, but welcome to the wonderful world of auto trannies. You may well have noticed my post on "auto to manual swap. " This is because a year ago I was where you are now, and it only got worse from there.
My first transmission blew, not due to power, but from a bad U-joint. It was so bad of a vibration that it finally cracked the tailhousing in half at 70, and in one swift stroke leaked all the fluid thus torching the whole innards of the transmission.
Had it rebuilt. Blew up 6 months later. My motor had ripped through the torque convertor and sprayed pieces of it into the rest of the transmission. Once again, torched. Covered under warranty, rebuilt it again. "All new parts. "
Another 6 months or so, truck stops moving after getting on the freeway. Big red puddle. Hmm... chalk another one up. Took it to a different shop. They did a pretty good job all in all. The replaced it with a reman unit from their warehouse as opposed to rebuilding my POS.
Here I am now and its acting up again. Still driveable... only a matter of time though.
Now that that's out of the way, though. Lets try to make sure you don't end up that way.
First off, as DP said, "tuning for longevity" is absolute horse apples. One big enemy of auto trannies is gear overlap. What the means is on a stock transmission when it shifts from 2nd to 3rd, the clutches don't release for 2nd right away, but the clutches for 3rd do engage, thus causing overlap. Something has to slip, of course, so both sets of clutches slip and cause heat buildup and wear material in the fluid. The point of overlap is smooth shifts, for a smooth ride. If you ask me, if you were lookin for a smooth ride, why would you buy a 15+ year old, leaf sprung, solid front axle, heavy duty truck?
What they do is reduce the amount of overlap in the clutches, causing a harder shift, but actually improving performance of the transmission by reducing slippage, and extend the life.
The slipping you talk about is a problem I have fought with for 3 years. Its generally a 2nd to 3rd shift, it feels like it hits neutral somewhere in between the two gears. With all I've done to my motor, the truck moves out pretty good, and when that slip happens you literally get thrown forward in your seat, and then thrown back again when it finally decides to hit 3rd. My newest transmission, the one in right now, doesn't do that. So let that speak for itself on the thought that the problem cant be fixed.
I cant figure out exactly what the issue is, if the transmission can't decide between which gear to be in, or if its something worse like gears not engaging right or something. If it is that the transmission can't decide, I have a thought that maybe you could try adjusting the throttle position sensor, "tps. " Which is actually an instrument of satan charged with the job of making you use many many profanities.
Jb, I hate to be the pessimist, but welcome to the wonderful world of auto trannies. You may well have noticed my post on "auto to manual swap. " This is because a year ago I was where you are now, and it only got worse from there.
My first transmission blew, not due to power, but from a bad U-joint. It was so bad of a vibration that it finally cracked the tailhousing in half at 70, and in one swift stroke leaked all the fluid thus torching the whole innards of the transmission.
Had it rebuilt. Blew up 6 months later. My motor had ripped through the torque convertor and sprayed pieces of it into the rest of the transmission. Once again, torched. Covered under warranty, rebuilt it again. "All new parts. "
Another 6 months or so, truck stops moving after getting on the freeway. Big red puddle. Hmm... chalk another one up. Took it to a different shop. They did a pretty good job all in all. The replaced it with a reman unit from their warehouse as opposed to rebuilding my POS.
Here I am now and its acting up again. Still driveable... only a matter of time though.
Now that that's out of the way, though. Lets try to make sure you don't end up that way.
First off, as DP said, "tuning for longevity" is absolute horse apples. One big enemy of auto trannies is gear overlap. What the means is on a stock transmission when it shifts from 2nd to 3rd, the clutches don't release for 2nd right away, but the clutches for 3rd do engage, thus causing overlap. Something has to slip, of course, so both sets of clutches slip and cause heat buildup and wear material in the fluid. The point of overlap is smooth shifts, for a smooth ride. If you ask me, if you were lookin for a smooth ride, why would you buy a 15+ year old, leaf sprung, solid front axle, heavy duty truck?
What they do is reduce the amount of overlap in the clutches, causing a harder shift, but actually improving performance of the transmission by reducing slippage, and extend the life.
The slipping you talk about is a problem I have fought with for 3 years. Its generally a 2nd to 3rd shift, it feels like it hits neutral somewhere in between the two gears. With all I've done to my motor, the truck moves out pretty good, and when that slip happens you literally get thrown forward in your seat, and then thrown back again when it finally decides to hit 3rd. My newest transmission, the one in right now, doesn't do that. So let that speak for itself on the thought that the problem cant be fixed.
I cant figure out exactly what the issue is, if the transmission can't decide between which gear to be in, or if its something worse like gears not engaging right or something. If it is that the transmission can't decide, I have a thought that maybe you could try adjusting the throttle position sensor, "tps. " Which is actually an instrument of satan charged with the job of making you use many many profanities.
Weelllll, I could tell ya, but then I'd haveta kill ya. Then I'd go to jail and never get my cab swap done. So I can't tell ya. 
