Gonset G-50, two versions?

   Following up on my original post:
   I've found no information regarding any obvious external differences between the single and dual-conversion G-50's, but with the help of a better manual and schematic, from Manual Man, I've looked into the internal differences.
   In both versions, the first half of V8, a 6U8, serves as the first mixer (the only mixer, of course, in the single conversion model) while the second half of the tube is the free-running local oscillator to create the 2.3 mhz IF. In the single conversion model, V9, a 6BH6, follows up as the first If amp. For the dual conversion model, Gonset cleverly replaced the 6BH6 with a 6BE6—a pentagrid converter—and added a tuned circuit from the cathode to grid #1 to create a second free-running local oscillator, so that V9 accomplishes the second conversion (455 khz) within a single tube. Practical, efficient engineering; no drilling and blasting or additional tubes. I suspect that the free-running oscillator might have been less than ideal for an SSB receiver, but for AM it was fine.
   So while there's no difference in external appearance, there is a visible internal difference, which can be seen by looking through the perforated cover (a flashlight is handy, here). With the front panel facing you, and looking down at the chassis from above the rig, you'll see four IF cans in a roughly rectangular arrangement near the left side and just forward of two metal can filter caps. There's a tube between those IF cans, and that tube is V9. Look closely; if you see an opening for a slug-tuned coil near the tube socket, it's the dual conversion model. That slug-tuned coil, mounted on the underside of the chassis, is L12: the tuned circuit for the free-running second local oscillator. The single conversion model won't have that coil, of course.
   A cautionary note: there's a document floating around on the web, titled "Chassis Layout & Adjustments, Gonset G-50." I don't believe this was ever an official Gonset document, and a bit of text attributes it to KW05. That call is still active but it's a vanity call, so I don't know if it's the same ham. It's a handy sheet, showing the tube layout and giving some hints on adjustments and modifications, but there's an error: the document shows two tubes designated V10, including the tube between the IF cans, that I mentioned above. In actual fact, the tube between the cans is indeed V9, and the document labels it incorrectly as V10.
   Here's an interesting twist, though: I've got two G-50's, and yesterday I pulled the covers off both to verify whether they're the same model. One of them had a 6BH6 installed in the V9 socket, so I figured it must be the single conversion model, but then, I noticed that the opening for coil L12 was present. Turned it over; sure enough—it's got the correct circuitry for the dual conversion model. Yet it works with a 6BH6 in place of the 6BE6! The 6BH6 is not a pentagrid converter like the 6BE6—it's missing two grids—yet enough of the connections are correct—heater, cathode, plate, and the existing grids—that it still performs the function of a pentagrid converter. I would think that a real pentagrid converter, engineered for the purpose, would work better, but it surprises me that the 6BH6 would function at all in that application.
   It's part of the fun of old boat-anchors, and electronics in general, that sometimes we find ourselves scratching our heads (maybe that's what happened to my hair) and questioning some of our basic assumptions.
  Fun stuff!