WHAT REAR END LUBE DOES MY 2002 TAKE? 80/90 OR 145? Broke down in KY

[BryanH]

Rearend or tranny sparted to pop/vib bad after I put a atv in the bed and pulling a small 19' boat. It is so bad I pulled over now in Fraklin,KY. I went from home to Canada/VT and now heading back home. I want to see if I add fluid it might change it so I know it is the rearend and not tranny. I am at 427K on all stock parts so it could be either.
I am at the Pilot truckstop waiting for reply

[greasyF250]

I put in a new ring and pinion gear and I put in 75-140 synthetic. Just checked my owners manual and it says 75-140 motorcraft synthetic. I have a 2000 F350.