I've located a Gilfillan that has the 5S8-52105 number stamped on the chassis( under which is G2)... with a 5W4,6F6,6Q7,6K7,6A8 tube line-up.
So this seems that it is a 5S8.

AND...Now when I lookup this 5S8 schematic here:
http://www.nostalgiaair.org/PagesByModel/587/M0008587.pdf

I get very confused because right on the 5S8 print there shows a small inset sketch of the chassis with those same tubes as listed above... so far so good...

However, the schematic drawing actually shows different tubes ie:
80, 42, 75, 78, 6A7

What gives??

If the schematic is otherwise the same as your radio, they may have made a tube change mid-run. The tubes in the schematic are identical to your tubes with the bases as the exception.

Thomas

Peter,
What Thomas says about tube lineup changing while still in production is consistent with the MYE book. It shows both tube lineups. Same schematic is referenced (Rider 9-2).

Richard

Ok great! Thank you.
I was rather confused... which is easy for me lol
I looked up the tubes first and did notice that only the bases were different..
BTW
I've also been hunting around for an MYE book now too. Found one 6th edition for $45...
guy says he just moved and will need to search for it... so I'm still keeping an eye out