I am cleaning my sm420 trany up and installing new gaskets. I saw online that there is an upgrade to the front shaft by Novak that replaces the front input housing, and they grind a new seal area on your own shaft. I have the ability to do this myself, as, I have a universal tool and cutter grinder, a nice Romi lathe and Bridgeport mill. I can grind the shaft between centers, make a new input housing, and install a new lip seal. Has anyone done this upgrade recently? I would need the seal number, and the shaft dimension, that way I can do it myself. This is a 1948 sm420 that is in really great shape. I am also considering a Gear Vender overdrive unit. The truck is a 47 3600 with the 4:56 ratio, but in very good shape too. I found a 4:11 center carrier, but the guy is a little hard to deal with, so an overdrive will be my next choice for better road drivability. Any info will be appreciated.
