^^^ Oh yeah...
A few months ago, I bought a spendy metal-backed repro pad for my K10 because its pad is utterly fragged.
You'd think that if anything would fit & be right, it would be a $500+ pad for something GM.
Not even close, couldn't get it to fit all all decently, gave up after a full day of wrestling/trimming/trying to get clips to fit, etc.
It IS a more complex deal than a '68-'70 B-body, or A-body, but be sure they have a decent return policy just in case.
After that cluster**** was over, it cost me about $100 to learn that even GM stuff can be off by a bunch.

If at all possible, a mint original OEM pad is the way to go; I sold a couple '69-'70 B upper pads last year for $250 each, so they're out there...