This mysterious device showed up on the FCC website today, it's the PRO-162 by Uniden.
A 2000 channel triple-trunking scanner, made for RadioShack.
At first look it's nothing new, 25-1300mhz range with the usual gaps. EDACS, Motorola and LTR trunking. Weather Alert, Signal Stalker.
There was also a mention in the manual it would interface with the PRO-433. I'm not sure how it compares to the PRO-528.