AeroDynics, that were either gear or chain driven, had a data plate listing the model number as well as a series of letters that denoted that particular lightbar options.
H= Halogen lamps
CF=Crossfire, mouse ears style
CF-SB= CF as above, Series "B", CrossFires that are independent from each other.
T or TT=Takedown light, single or double
Q=Quartz Halogen Bulbs
Z=custom job done at Federal
S=Small size frame
M=Medium size frame
R=Single direction cascade mirror flash
X=Front and rear cascade mirror flash
RWL=Single Direction cascade mirror Wrecker Lightbar
22 = 4 sections minibar
24 = 3, 3 1/2 and 4 sections lightbars with speaker center
25 = All-Light 10 sections lightbars