[Milsurplus] Clevite ceramic filter PN decode

[antqradio@juno.com]

Greetings

Anyone able to decode Clevite ceramic filter model number markings
(55D85C)?
Not as straightforward as some Collins mechanical filter numbers.  They
are about a quarter the volume of 
their mechanical counterpart and appear to only have 3 dB insertion loss,
according to their web page.

I found 4 NOS units in a junk box at the Fort Smith Hamfest last
Saturday.
Any information appreciated!

Regards from Arkansas,
Jim