RCA Identification

I have an RCA tube chassis which only has a large tag on it with patent numbers and a serial number. It has 3-24A's, 2-45's, 1-27 and an empty 4 pin socket. The chassis does not appear to have any info next to the sockets saying which tube should go in it.
The chassis is 14 5/8 " wide, 10" deep, and 3 1/4" high. Any help identifing this unit would be appreciated.
Thanks, Vince

[ekimetsok]

Pretty safe bet that your empty socket should have an 80 rectifier in it.