Two Speed Transfer Box

[Grant Bowker]

I'm finally ready to take a stab at answering this.
Using the parts listings for the C60L and F60L as source:
For the front axle declutch assembly the housing, shaft, shift fork and the clutch to engage into the transfer case proper all have common part numbers so although I didn't check it seems the whole assembly is the same.
For the PTO assembly the housing, sliding clutch, bearings, shift fork (also a common # to the front axle disengage fork) share coomom part #s Ford & Chev, again I think the whole assembly is probably the same.
Transfer case output shaft and gears has same part # for both types, idler shaft and gears have same part #s, input shaft and gears also have common #s between brands.
The case housings have individual part #s for the 2 brands.
On what I can see, it looks as if both makers used the same or at least similar internals (most seem to have GM style part #s perhaps indicating designer?) within their own cases. The bearings that I checked seem to be the same part #s but I didn't check to see that all of the cones pressed into the case were the same (could have used the same bearing with different cones to match different size holes in the cases).
Perhaps different chassis led to different mounts (and as has already been mentioned different designs for mounting the T case shift) and thus different cases?