Going through old parts.

Hello folks!! its time to give out a door prize.
When my wife gets home I will post pictures of them.
I picked this set of good looking exhaust manifolds up years back.

Part number left side = 53010187.
Rightside= 53010186.
With W3 and maching 2869 number on the pair.

Intake size 1"3/4 tall and 1"3/16 wide.ID
the exit hole is 1'7/8.ID
They both dump out the back at a scoosh over 45 deg.

I was thinking at the time they where good flowing manifolds.
I was turning left on dirt in them days and I can't remember what 360 they came off of. I am sure they where 4bll manifolds.
So far all I can find is 73 and down part no# on all the serch places on the net. So if you have any knowledge on this or secrets let me know how and where to go.

or your thoughts Thanks Mike.