[Milsurplus] Nomenclature request

[Todd, KA1KAQ]

Got a pair of odd ducks here, need some expert help. 

Racal RA17 apparently rebuiltmodified by RCA to/as:

RECEIVER, RADIO

R-1513/FRQ-15(V)

Serial   AIO

Manufactured for

NAVY DEPARTMENT - ELECTRONIC SYSTEMS COMMAND

                              by

RADIO CORPORATION of AMERICA

blah blah blah NJ

Also another RA17-C12 modified by 

ELECTRO-PHYSICS LABORATORIES

ELECTRONICS DIVISION
ACF INDUSTRIES, INCORPORATED

HYATTSVILLE, MD

Googling turns up nothing but a hit for ACF in 6-Land making some
radar system for Gemini. Zippo on the RCA modified rig.

I'm sure most are aware of the defense industry and 'other' stuff in
Maryland, but neither of these rigs have an "Intelligence Agency
Black" panel. Just the typical Racal light gray/pale blue. shhhhh

Just curious to know if anyone has past experience or knows what the
modifications would include, or how they would affect standard
performance.

Thanks - 

~ Todd/'Boomer'  KA1KAQ