The 4 speed has the reverse lockout lever. And yes, it is preferred because of the granny first gear and heavier u-joint yoke and trunnions. Great for parades, pulling up stumps, and towing other vehicles that need a helping hand. ;-)
The 3 speed, which was standard for 1927, has the smaller u-joint yokes and trunnions; the same parts that were used for cars.
The trunnions are made from steel. I have no idea about hardness.
The inside diameter is a straight through bore, but the outside surface is domed. Also, one side of the ID has a bevel cut into the edge so as not to interfere with the curved inside edge of the yoke trunnion shaft.
While you're inspecting this area, what is the condition of the front drive shaft bushing in the torque tube? Mine was worn enough to allow the drive shaft to be wiggled sideways about 1/16 of an inch. Luckily, I found a NOS bushing (part number 345734) on ebay for $20. Score!!
There's a cork seal and a steel flat washer behind that drive shaft bushing. This seal is meant to keep the oil in the u-joint area from leaking too fast back into the differential. When I took the seal out, it crumbled into pieces. Not surprising for a cork washer that is 96 years old.
I went to a local bearing house and they determined that a new 11730 CR neoprene seal could replace both the cork seal AND the steel flat washer. This new seal is .040" thicker that the old cork and steel set up, but I think it will work okay. I have not installed the new bushing and seal yet, but I will report what happens when I get to this part of my rebuild of this area in Lurch.
The devil is always in the details!
;-) Dean
