"Rare" original dealer seat riser blocks

Whoa.

I think I had a set of those in my 73 Challenger.
I just assumed someone made them and put them in.
I threw them away because I'm also 6' 3" but with a long spine.

Is the end grain painted real good, like a couple coats to make up for being absorbed by the wood? How about inside the holes?

Where did you learn about them being dealer items?