I provided PennGrade Classic GL-4 80W90. I KNOW that is what in used.
the ZF had been in barn storage for 3 decades with oil in it.
Ron Mccall rebuilt 4/16 and it remained in warehouse storage till mated to engine couple years ago. first test driving 12/23
there was no bad smell when drained. hard to tell new from used, the new has a blue tint.