1969 C10 cab mount question

[Artofdeath]

I am doing the cab mounts on my 1969 C10 and was hoping someone would be able to answer this question for me. When I took the old mounts off I had these cups on my mounts.

https://imgur.com/lj94Qjz

Are these cups supposed to be used on a 1969 C10 or did the previous owner use them from another vehicle? I have searched and have not been able to find pictures of them on a C10, that is why I am questioning the situation.

I would like that thank poster "In The Ten Ring" for posting a pic of cab supports in an older thread. I did not realize the front mounts were a different thickness from the rear. Saved me from messing myself up! Huge help so thank you Sir! This site is invaluable.

Picture of mounting hardware was in this post...
http://67-72chevytrucks.com/vboard/s...d.php?t=689476