I have a 2001 Excusion with the full banks powerpack (100hp chip) and the transmission has developed a massive leak, I suspect from the front/TC seal. I am debating if I should just replace the seal or have the whole thing rebuilt since I need to pull it out of the truck anyway. It has just over 80,000 miles on it.

To add to the complication, all drivetrain mods were made by the previous owner. The work was all done by a qualified shop, and from what I can see was done very well. The problem is I am fairly certain the transmission had extensive mods to survive behind the 400+ HP modded powerstroke motor, and I don't want to just toss the current trans as a core, but I don't have the details of the build. Other than the leak, it works fine.

The truck doesn't tow much, but the right pedal gets used pretty hard. With 80k miles, should I even consider only replacing the leaking seal while the trans is out of the truck?

Can anyone recommend a perfomance shop in the Northeast (I'm in Rochester) than can do a better than stock rebuild and retain the good parts of the tranny I still have?

 

I would replace the seal if it shows no other signs of damage. No codes, no slippage, not running it hot, fluid looks good.

I just replaced my factory 4R100 in my truck and it has 230k on it. 130k of that was with a lift, 35" tires, chip, exhaust, 6637 and it is driven pretty hard. It also tows a 10k 5th wheel.

It's ultimately up to you, but I'm a believer in "if it ain't broke don't fix it". Of course I also believe in preventative maintenance. FWIW, I pulled my trans at 185k to replace the flexplate.