Yeah, actually on the 70 Challengers some were and some weren't, had a whole other post on here about that lol. This one did not. It was on the cowl though.
Some are stamped on the top of the upper support and some on the side of the upper support. Some may be covered by the antifreeze decal.
If yours is missing and the cowl is stamped I would suspect it was replaced before. Either way it doesn't matter now.
The lower butts up against the two "L" shaped brackets that are on the frame rail.
The top only really goes on one way.
I could measure all 7 of my Challengers and I bet no two are the same if I measured from the upper support to the firewall.