How does a pre-1972 SPID designate GMC or Chevy? SPID example for GMC?

[71CHEVYSHORTBED402]

This GMC decoder for a 70-71 GMC shows just five digits for a serial number.

The 67-72 decoder shows six digits. Is that the only indicator on a SPID that distinguishes a GMC from a Chevy in 1970-71? Edit, nope: The VINS differ in a number of ways.

Thus real life example KE141Z654372 must be a Chevy? It's a SWB (model KE10734), I don't suppose many Chevy SWB K10 were built. FWW, the truck's build date is on the same day as my SWB C10, separated by <200 trucks, both serial and sequence numbers.

K = 4WD
E = V8
1 = 1/2 ton
4 = Pickup
1 = 1971
Z = Fremont
6 serial numbers