Hi Bill: I believe that's a Guild Model 40T (tremolo); no guess on the date of manufacture but I think the seller has the tubes ID'd correctly. The 12X4 rectifier is the same thing as the more commonly seen 6X4 except that its filament is designed to operate on 12VAC, not 6VAC. As with the rectifier, the 12AB5 output tube is the same as the 6AQ5 except that it too runs on 12VAC. Since the 12AX7s run on 12 volts (6 volts but wired humbucker), using all 12V-filament tubes allows the mfr to buy a transformer with only two secondary windings; high voltage and 12v instead of the more common three secondary windings; high voltage, 6V for preamp and power tube heaters, and 5V for filaments in the 5-series family of rectifiers; 5Y3, 5UA4, 5AR4, GZ34. The 12AB5 in Class A (single-ended like this amp) is rated at about 5 watts.
The seller is a member here although I don't think he's posted recently. This amp has gone around a couple of times on eBay and one like it from a different seller was threaded here not too long ago. This seller remarked that he understood from discussion here that some of these models were made off-shore. Without being completely certain, I think the 40-series like the auction amp were made in the US but many/all(?) of the Model 50Js were made in Japan; identified by the open lugs on the bottom of the power transformer (shown below on the right) and the widespread use of electrolytic capacitors in the signal circuit (all the gray cylinders on the left).
CJ
