its short for power amplified microphone. some ham radios will power them or batterys like you mentioned. it just means they are amplified.
pull the cover off the bottom and see how many wires are connected. if you see a yellow and blue wire it is a tug 9. if it had a shield, red, white, and black with no yellow or blue its a tug8.
you have the best base mic you can get. many people prefer the eagles over the d104's but im oldschool and prefer the d104's.
there are a few different mic's
d104 (like you have)
tup d104 (key on base and stalk)
d104 special edition (black base, chrome stalk,black head with base bar)
silver eagle (all silver)
night eagle (black and brass like you seen)
golden eagle (gold silver eagle with nameplate/ serial number)
diamond eagle (golden eagle with small real diamond on back)
final edition silver eagle (final run of astatic base mic's)
there are also "k" eagles, they have a multi-tone ets (roger beep) or morse "k" beep.