I have a 1991 ranger w/2.3 litre nnon 4 wheel drive. Any way my differential was seeping fluid and did not want to chance killing rear end and way I pulled read cover to change fluid and to replace gasket anyway .I need to find out what fluid to put back in it .one website said transmission fluid and another one said 80-90 w .called my nearest dealer and they said they couldn't find it . Anyway if anyone knows what to put back in it would be.a great help .and ahead of time thanks for all the knowledge I've read on this site.

 

Your rear differential/axle housing needs about 2-3 quarts of 80-90 weight gear oil.

 

Thank you so much for that info .called dealer and they couldn't tell me

 

Here is a quick How-To with other info on the Ranger front and rear axle fill

Ford Ranger Differential Fluid Inspection and Replacement