New viscous units are available that are still made the same way. In other words, they look the same. The actual finish color may not be exactly the same as the ‘70’s was. I’m not sure. But below is a new one I picked up for a project.
The units are not rebuildable.
N.O.S. is not available
Tony may indeed have a original unit in stock.
A possible way around to keeping it exactly OE looking is to get a new one and address the finish and stamped numbers. I think the numbers being the harder to reproduce.