[Ron Ramirez]

6C6's and 6D6's can also be use in place of 78's...

Sorry, but I have to disagree. In my experience, Philcos do not like 6C6 and 6D6 tubes; they want to see 77s and 78s, respectively. Even though the tube books say that 6C6 can replace 77 and 6D6 can replace 78, the Philco sets I have worked on have performed better when they have the tube types they were designed for; that is, 77 and 78. Sometimes it took installing a 77 or 78, as appropriate, to turn a non-working Philco into a working Philco.