The Stovebolt Site Forums The Parking Lot Big Bolts Aux Trans anyone recognized this??? ID-ed Aux Trans

As far as I know Watson was the only manufacturer of this small of an auxiliary, but I wasn't aware that they made one to be married to a SM420. As wide as the splits are on a SM420, there is a good chance that it will be progressive. But I can't imagine what you would do with 12 speeds behind a GMC.