Swapping internals 904

SWAP ALL OF THE GEARTRAIN, the late trans has a different type of splines on the output that MUST be matched to the planetarys. Get it wrong and the trans will fail in a few miles. BTW,
when this happened to me, and when I took it apart,
I could not see a difference. I ended up throwing all the geartrain parts away from both transmissions and pirating the guts from a third trans! Sheesh. No more problems.

Don't forget that by '85, most of those V8 transmissions were Lock-ups, as Kim alluded to.
I found a few visual internal differences between the lock-ups and the nons. I did NOT study it out, as I had lots of transmissions to choose from, so just kept it in the family.
Keep the ValveBodies with the cases.

I would not do this again.
I would just rob the normal-wear parts out of the built trans, but if the slanty L/R band is the more narrow one, you probably don't want that low-capacity band behind your V8. So then; I would just rebuild the V8; the kits are cheap.
And besides that, the slanty VB is programmed differently, and the governor will be different too. So if you mistakenly forget to install the V8 governor parts, you might end up taking the tail off for governor tuning, possibly more than once.