Correct motor mounts?

[JBB]

I have a L-78,69 SS, and I purchased a set
of N.O.S. pieces for our car a while back.
On the Part sticker on each Moter/frame mount are the #'s 3980941 and 3980942, respectively. I think the last four digits
of the number are stamped into the frame mounts also, on the lip that the bolts go through to the frame. Now I am not sure as to the fact that these are service replacements, or the actual assembly line parts. Joel