[mwoodruff]

Thanks to everyone who responded; it’s great when these forums work well.

It now seems that I may have a 16b and not a 17b.

I base this on Some small differences in the tube layout diagram (or what remains of it) in my cabinet compared to the ones that radioroslyn posted (thanks!), as well as the fact that the dial indicator has at least four scales (barely visible).

Also seems that the set was sold by Sears, Roebuck.

I have posted two pics, including the chassis on the workbench that I share with my wife in the dining room.