[Arran]

My understanding is that the first production were 121 and later 125. Don't know of any other chassis' for the 38-116. Nostalgiaair only lists the two. But if Ron & Chuck differ, don't mind me.

I'm not expert on this but I think that many are getting confused as to what the code numbers mean. In Philco jargon "Code 121" always means the original production design of whatever model it is, it does not mean that it was early production, if it has also production run number that's what will tell you whether it was late or early production. Now the higher number codes mean that they made different production versions to accommodate whatever parts supply they had on hand, (usually involves tube changes) so if there is a Code 122 and a Code 125 then there has to be a Code 123 and 124 as well, since Philco was a huge company these could vary from week to week. I can give an example of this, the Philco 46-1201 "Bing Crosby", there are no less then eight code numbers of Codes 121-128 with production runs marked 1 through 4, and they weren't necessarily produced in a linear fashion. You could have a Code 121 set made in production run 3 or a code 126 made in production run 2.
Regards
Arran