Dang it...the 700 on my 92 Bird just lost the engine braking, assuming its the sprag that everyone talks about. Trans still shifts quite firmly, and isn't slipping at all that I can tell, but I have zero engine braking. Should I be planning on rebuilding the trans in this soon (or more likely collecting parts for a 5speed conversion), or is this just going to be a nuisance for the next 50,000miles?

 

Well it is probably your overrun clutch, sprag, or hub assembly. I just fried mine about a month ago. Same deal no slips just no engine braking. I broke my overrun clutch hub, which in turn burned up the clutch. This clutch only has 2 friction discs! If you keep driving on it you will only cause more damage, metal shavings and such will find their way through your entire trans. Its time for a teardown. Sorry about your luck, I felt your pain.