[TMC] GPR-90RXD design changes?

[Mahlon Haunschild]

Hello, list.  First time poster here.

Picked up a fairly nice GPR-90RXD (s/n 103) over the weekend & noticed 
that it deviates from the web site's schematic & GPR-90 manual in a 
couple of ways:

V1 is a 6DC6 (GPR-90 manual and GPR-90RXD schematic says 6AB4)
V2 is a 6BA6 (GPR-90 manual and GPR-90RXD schematic says 6CB6)

Both changes are obviously factory as the tube type is stamped on the 
chassis (but in a different font than elsewhere on the chassis).  Were 
these production changes to the GPR-90 design somewhere along the way? 
ANyone have the correct manual/schematic for my receiver that I can 
wheedle a copy from before I stick my head into the restoration process?

regards,

Mahlon - K4OQ