How, long ago did you rebuild the engine ?
The reason I ask is on reassembly you may
have damaged the seal in the trans.
I replaced mine whenI did the engine too,
looks like a pain to change, until you know
the secret, go get a cheapy dent puller with a
2 LB slide hammer on it, pierce the seal with
the screw (on the end of the puller) and slide
hammer it out, slick and easy.
I got a reaplacement seal from a bearing place,
these seals are a silicone lip type, and I bet $20
from the dealer, I got one for $5 waited 1 day for
it to get there, and picked it up, take the old seal
for # cross reference, best way to get the right one
Wild