The ring and pinon from Jim Carters will not work for a 3/4 ton. The 3/4 ton has a third member that attaches through the front of the diff. But I did gat a third member from a 65 chev, 3/4 ton which was a bolt on, all I needed was the gasket. That took me from a 4.56 to a 4.11 ratio. I can go 70 now, but do not like it. I used a GPS to check my speed, 73 MPH was enough for these old trucks!