[Milsurplus] R-388B/URR receiver?

[Nick England]

OK that is not a typo. I just got a 1963 manual listing Navy
electronics equipment by federal stock number.
R-388A/URR    FSN 5820-557-5140    cost $1160
R-388B/URR    FSN 5820-897-8314    cost $1220
                      added to the Navy Supply System 8/61

Anyone ever heard of an R-388B?
Man, I've been looking for a photo of an actual R-388A for years, now
I find out there is a B model too!
cheers,
Nick K4NYW
http://www.navy-radio.com/rcvrs/r388.htm