Here are some part numbers posted by Baron owner Mike T. as replacement possibilities for his three Baron light dimmer rheostats from Newark:

Ohmite Data Sheet HERE

Ohmite from Newark HERE

Mallory Data Sheet HERE

Mallory from Newark HERE

Here are some helpful Ohmite Catalog Excerpt #1 and Excerpt #2

Here is a solid state option: Max Dim

Not exactly CSOB styling on the price but seemingly a very effective solid state dimmer.

Don't forget to replace as many of your incandescent post lights as possible with LEDs to reduce your current load (and the heat the rheostat has to dissipate) on the rheostat.