This may be just a dumb question but.......I had my "shift shaft seal" replaced right after I got mine in December as it was leaking. Is that the same part you're talking about? If so, the part number on my receipt is 8-08644-709-0.....$8.35, and $98 labor.

I happen to have one of the remaining "authorized" Isuzu repair places near me, and who did the work....wonder if that has anything to do with it?

Just thought I'd mention this in case it's the same thing as yours.