Hy Drydock, unfortunately it's not all that easy. The old sliding gear transmission has a smaller bolt pattern than the SM420, add to that the fact that the clutch/brake pedal shaft is bolted to the bellhousing. There is no factory bellhousing which will allow the swap. Apparently Jim Carter sells a bellhousing (custom) that will allow this swap. I do believe the SM420 is a bit longer than the sliding gear transmission, so a driveshaft adjustment will probably have to be made, good luck with the swap.
