Is this original?????

[57taskforce]

Truck in question is my ‘72 K20 Cheyenne with factory AC. All the vacuum tanks I’ve ever seen on these trucks are the round plastic type. This one looks like an old soup can... but, look at the bracket that mounts it to the bracket on the outer housing. It looks almost too good of quality to be a back woods Bubba job. Almost like it was manufactured... did any of these trucks have metal cans? I think I know the answer already but just curious... here’s a few pictures.
Before any one says anything I’m going to replace the rubber fuel hose with stainless and replace the air filter.