It has been some time since I have been on the site, and me and a co-worker, who is a diesel mechanic, though routine stuff for our trucks, not mods- I remember posting here a couple years ago, talking about trans life expentency when you "turn the wick up" a bit on these, that they were one of the first mods-

So tell me, why does the tranny fail (BTW- I have a 98 12V QC dually 4x4)
on these trucks (auto trans of course) , and what are the mandatory fixes?

What is the max HP you should be able to get out of a trans and still have it live? Or max Torque would be more appropriate?

On a bit of a side note, my co worker friend couldn't believe the times I was reading off from vids, I think I got them off this site, times in the 1/4 anyway, and believe that there were not purpose built race trucks that could still cruise around the nation towing horses or whatever?

Can you tell me the lowest 1/4 mile ET numbers for a truck that didn't have it's longevity seriously, and I mean seriously compromises? Were hiway speeds obtainable and comfy as stock in the interior?

 

If you change the oil and filter frequently you can probably get some more life out of it. Maybe good expternal cooling and filtering as well.
The stock convertors are weak, especially the convertor clutch. Supposedly its common for them to overheat and distort the surface and contaminate the oil.
Also a good valve body will raise the pressures so youve got more force on the clutches to hold them.
Theres piles more aftermarket goodies out there. I was told if youre over something like 450hp you should also look into a billet input shaft since those are prone to snapping. Of course this will be more torque dependant, and I dont know the torque generated at that HP.