[Ron Ramirez]

I have the same sheet. Maybe I'll post it later if time allows.

As I recall, there were three different versions of Model 71:

Code 121/221: 550-1500 kc, no shadow meter. Large tube shield on side of chassis similar to Model 70 shield.
Code 123/223: 520-1500 kc, no shadow meter (although late production models may have the shadow meter). Large tube shield.
Code 126/226: 520-1500 kc, with shadow meter. Individual cylindrical tube shields around three "front end" tubes on side of chassis instead of one large shield.

Differences in Codes:

121, 123, 126: Single speaker (chiefly cathedral models).
221, 223, 226: Twin speaker console models.