I think you need too start over and pull it out and inspect the case for cracks,i have seen many leaks but not from the top of the case,unless it is blowing out the dipstick and running down.
The overdrive going out is the end result of the problem you haven't fixed yet.
If your builder is just replacing burnt clutches and nothing else you haven't fixed the problem.
If you pull the o/d out and replace it it will happen again

Like I said above, the trans works fine, shifts great and the fluid smells as good as that nasty stuff can smell! I do believe the trans needs to come out, I tried to find out where the fluid was leaking from with no possible way to see it.

Anyone know anything about this company and product?

http://www.dttdiesel.com/product-p/dttod.htm

Thanks! I know about Gorend but didn't see a ready to go overdrive unit, maybe I need to look at little further...

i saved the attached image about reliabilty mods to the OD, maybe posted here on Moparts or another board.

The image may be from DTT, or Sonnex

My original 46RH Overdrive unit from 1995 with about 200,000 miles on it is now slipping on any hill over about 2% grade and i am looking for someone to rebuild it

I also found that there is no mount for the OD unit and it just sits above the skid plate rattling around until it breaks. There is an aftermarket mount kit I will be buying when I get the new OD unit.

Yes, TCC is ok and there is no slippage in locked up third gear

If you were further south or west I could recommend someone. Find a trans guy(over 40yrs old) that builds for the local racers(they can give you names) and go with him,it's not hard to do.