Defrost Vents???

[DeBattista]

So, I have been researching and can’t seem to find an answer.

When I purchased my 72 2WD C10 it came with a pretty decent supply of NOS parts the PO had bought for the truck to complete the work he had planned. In that pile of parts were (2) NOS Defrost Vents.
(1) Black LH Vent PN 341756 and (1) Saddle RH Vent PN 3989620

So in all my research on these vents anytime an NOS set or single is for sale, it is always this same combination seems to be prevalent (RH Saddle and LH Black). And I cannot even find a PN for the Black RH vent (Casting numbers on the part are identical: I’ve found photos of original used vents and the number on the part is the same on both the black and saddle vent).

Does anyone know why this might be or have the PN for an NOS original GM RH Defrost Vent. I don’t really want to paint the saddle one cause I’m sure whatever color I paint it with won’t match the black, so I’m contemplating just selling them and buying the aftermarket ones but I know they just won’t fit like these.