Ok, now I got it open, you guys where right, the rear clutch retainer is totally gone!
It totally burned the clutches, the steels are also bend from the heat, the clutch retainer itself also shows heat signs! Also the beleville spring got scratches and so does also the front planetary assembly on the teeth a little bit.
BOTH sealing gaskets of the piston (inner and outter) are partly destroyed. I found parts of the piston seal in the clutches!
I just checked quickly the band adjustment with the "snug" method: front band got around 2.5 turns, rear band I got around 4 turns!!
The rear band also looks a little bit used! You can see the fine lines in the band, BUT on a few spots they are gone... this band was also used more than normal, but not burned or so! That would also explain the 4 turns of the rear band!
That transmission is supposed to have alto red eagle racing clutches and red lined bands. The rear band is solid and ORANGE and the front is flex and ORANGE! I always had black and solid front bands on my other tranmissions, why is this one flex and orange? Aren't Kevlar bands black?
Anyway, it's orange, so are the front clutches (they look like new!) and the rear clutches, as much as I can tell since they are burned up pretty bad! So this few black parts I saw in the pan BEFORE I installed this tranmission are 95% sure sealing gasket from the rear clutch retainer piston, or what do you think? Or do I have Kevlar parts?
I mean, I got the first time this reverse problem after 15miles driving and that trans never saw more than 140F!
It just makes me sick that I had to remove this trans a 4th time, the torque converter is again full of dirt (I paid last time 300$ to send that back to the USA to open it, inspect, clean, weld and send back to me), I got again back pain AND working today on the car and lowering the car on the lift I hit something and that bend me the whole lower quarter!!!!!! I mean, it's more than just a few broken parts, it just makes me sick!
I want to know WHY that happened and IF this parts I saw in the pan before I installed it could have been the piston sealing parts!
This valve body is by the way a modified (not by me!) VB that shifts stronger. Could a bad VB cause something like that?!
Otherwise the other parts look fine, the front clutch retainer also thank god! Sprag also...

Here are the pictures:

http://home.tiscalinet.ch/6o4o/727

thank you for any help guys... really appreciate that!