<VV> 66 trans on 65 diff leaking

[Craig Nicol]

Al asked:
Guys,
A club member has a 66 4sp trans on a 65 diff - and is having leakage
problems.  Some of the manuals suggest this is a direct bolt on - while
(at least one) says there are mods that have to be made to make it work.
Can anybody clarify the situation for me - is there an issue with this?
Thanks,
Andy K.
Wisconsin

Craig replies:
Like Bob said, there are some issues with the fit. To expand on Bob's
comment: The differential pinion bearing adjusting sleeve is completely
different between a 65 diff and a 66 diff so there's interference there
which will crack the aluminum rear bearing retainer on the transmission when
the two are tightened together.  Also, the bolt that retains (oh I forget)
either the bearing retainer on the trans or the differential adjusting
sleeve doesn't have the right relief area on the mating component.  As if
that wasn't enough, the lubrication paths are different and in my experience
the lube oil transfers from one to the other and doesn't flow back; starving
one (I think that's the differential).  A solid gasket with no oil transfer
may solve that issue but the input shaft lubrication becomes compromised.
Whatever book said the two were compatible may not have actually tried the
combo on the road or made unmentioned modifications.  I tried this combo a
couple of times many years ago and concluded that it's much better to just
build a correct mating differential and be done with it.
Craig Nicol