[DeckApe]

The 6J8G is a production modification for the 40-180 (presumably there was a shortage of 7J7 tubes). I believe the connections are slightly different under the chassis owing to a different pin configuration, so draw a picture as to what connects where before you start on that socket.

This information and much more is available from Chuck Schwark and his Philco information service... As a customer, I can tell you it's well worth the $7 to have all the Philco-released info in your hands before you start.