I had a fresh 904(999) lockup trans built for my 390. Lasted less than 500 miles and lost all forward gears and reverse as well. I noticed some rough full throttle 1-2 upshifts lately and have another thread on that subject.

I don't know the status of the 999 trans and I am not sure what would cause it to lose all fwd gears and reverse as well. Should I do an autopsy and take it from their or should i just plan on an upgrade to the 727??? I did install a transgo shift kit in the valve body and I was wondering if I found an A-727 lockup trans would this valve body work or should I just go with a non-lockup and re-do another valve body??

This trans did not have the low band apply as it would freewheel in 1st gear when coasting. I did do some burnouts in 1st gear so I wonder if i did some damage????

FWIW, trans looks fine with no leaks and driveshaft is intact as well as the 8 3/4 rear......... TBF