Looks like its for checking the angle of the driveshaft to the universals. Should be a bubble level with it?
Service manual shows how to do it. But diagrams no photos if I remember correctly.
Chris - that 65 Satellite with the poly 318 at the Frostbite is for sale. It looks good down to at least 10', and you can drive it. How cool would that be? I've got more photosand a contact if you're interested. Guy's planning to swap engines out this winter if it doesn't sell 'cause he wants more power... Shame IMO.
Did you see the pics I posted of the 400 cid lean burn Magnum?
Ray - Did you see the moparts thread where the guy is asking about original lead for a points distributor? I assume you scan moparts now and then.