http://www.cbmuseum.nl/turner1972.pdf
The +3 B wasn't out yet in 1972
Based on the 750 series design,
Model +3 - grey hammertone
Amplified w/ compression,
Relay or Electronic switching (below)
300-3000 Hz frequency response
5000 Ohm impedance
SSK - black w/ chrome head,
Amplified
Additional gain limiter on bottom
300-3500 Hz frequency response
100 Ohm impedance
Model +3 B all crinkle black
- no switching underneath, 6 wire cord
(specs presumed to be the same as +3)
I know I found a later catalog the other day, need to locate it again.