I am trying to figure out what gears are in the rear end. Does anyone know what these came stock with? It was originally a 289 with a 2 barrell. It is now a 351W witha T-5 and I am wondering how to tell what is in there already so I do not replace it with the same gears. This is my daily driver but I want to make it a little beefier. I was thinkg 373 for the gears.