What type of oil do You use in a 1991 Ford Ranger with a 5 speed manual transmission?

In a 1991 Ford Ranger :

It depends on which 5 speed manual transmission you have

The Mitsubishi ( transmission code " D " ) takes ( 2.4 U.S. quarts of 80-90W gear lube )

The Mazda ( trans code " M " ) takes ( 2.8 quarts of MERCON automatic transmission fluid )