[Arran]

   I do have one 1629 tube and I might just try it in there. Although I have a lot of 6e5 tubes. If the 1629 is bright enough I will use it.
    I did find a fellow in eastern Canada who has some NOS 6X6 tubes and that is what he wants for them .. He also has some 6F7M tubes and he wants a fair price for them.  None of the tube suppliers on the net have these tubes.
 Thanks for the information about the 1629  Dan 

As yet I haven't owned a set that was equiped with a 6F7M nor had a need for a 6F7M. To be honest I had to look it up as I've never seen one, it was a pentode-triode tube designed and manufactured by Rogers Tube LTD., why I can't say, but I think it may have been intended for use as a combination IF amplifier and first audio since the pentode sections always seem to be used as an IF amp. Apparently you can either use a 6B8 or a 6P7 with some minor rewiring, depending on the application, often it looks like they would tie the plate and cathode together in the triode and use it as an AVC diode so a 6B8 or 6B8G will work. If lets say he wanted something nuts like $50 each for a 6F7M a rewire or a plug in adapter would be good enough for most.
Regards
Arran