I have a 47 1.5 ton. The original gearbox was filled with water running down the dash and dripping down the gearlever. I got another one just the same. Both are definitely SM420, 4 speed:
box #1 590474, date code j62
box #2 5834141, date code 11 67
Both boxes are full 4-speed crash. There is no synchro cones at all. It looks to me like they never had any. They both work fine but the teeth do the meshing.
Has anyone ever heard of SM420s with no synchro? Maybe we never got synchro boxes here in NZ.
