I picked up this radio thinking it was a 10S155. When I went to pick it up I noticed that it had an 8S154 chassis in it. Is it possible that Zenith put some 8 tube chasses in the higher end cabinets at the end of the production run? Or is it more likely that someone retrofitted it?
Thanks,
Joe

I would say the latter, however Zenith was good at mixing and matching.

If the chassis still has 8S154 printed on it, and/or the cabinet still has 10S155 on it, then I would say it never left the factory that way.

-Steve

The two model numbers described different combinations of chassis and cabinet. The paper sticker containing the tube placement guide should describe the intended configuration of the radio. If the sticker is missing or defaced, I'd suspect that a "frankenradio" has been created.

I once had a Zenith 9S-262 with correct cabinet and chassis but the paper tag inside the cabinet said 12S-265. Also had a Zenith 12H-670 cabinet with a 10S-669 chassis. Stuff happens.

Are you sure it wasn't a 10-S-668?

https://radioattic.com/item.htm?radio=0021023

It looks very much like the 12-H-670 but has the same chassis as the 669.

Stuff does happen, such as this chassis from probably a 7-S-582 has 10-S-567 printed on it… Whoops!

-Steve

"Are you sure it wasn't a 10-S-668?
https://radioattic.com/item.htm?radio=0021023
It looks very much like the 12-H-670 but has the same chassis as the 669."
You might be right about that one. They do look the same.
I know the 9S-262 was tagged wrong because I went to an antique store on S. Broadway in Denver one Sunday with my wife and we saw a dealer unloading the Zenith from his car. I saw the paper tag and thought wheee! a 12 tuber or some odd variant. I bought it on the spot. It was a mis-tagged cabinet, but still well worth what I paid.