Final Drive Part Number Question

[w30bob]

Hi Guys,

The TC-37F lists two final drive or drop axle housings. One is for Cubs made before '53 and the other is for '53 and above, with the difference being for the change in brake actuation. But the casting changed again for a third time at some point later on......but the part number didn't revise. I'm trying to understand why. The part number for the '53 and above is 350 806 R51, as you all know. But the later Cubs like my '77 had a different casting that didn't have the 350 806 R51 cast into it. Instead there is just an "IH" logo where the part number was in the earlier casting, and the casting date was still in the same place. This did require a new casting for the housing, so shouldn't the part number have been rolled to R52? I realize the functionality of the part didn't change, but when a casting physically changes didn't they change the Revision number? It also seems odd that they'd remove the part number from a casting and replace it with a logo instead. Anybody know why they'd do that?

thanks,
bob