I have a leak where the dip stick fill tube goes into the transmission. I assume there is a seal in there. Does anyone have the seal part number and experience replacing it?
Yes, there is a pretty easy to replace seal there. Sorry, don't have the the PN, but suspect available at any Allison dealer.
Might also be a good time to replace the "dead plug" seal on the other side of the transmission, as they tend to dry out and seep. This is where the dip stick would go in if mounted on the other side of the transmission.