[jrblasde]

Granted, it is huge for an output transformer, but I didn’t see anything else on or underneath the chassis recognizable as an output transformer so I figured that must be it.

But you are right! I just took another look at the schematic and realized that the output transformer is part of the speaker assembly. So yes, this chassis does feature a power transformer. Great clarification, Jim! Even so, based on the tubes and layout of the chassis it looks like the chassis still matches the model 610 as shown in the screenshots above from the 13th edition of Rider’s, and not the chassis style 610 of the 12th edition.