OK, here's the story. Mine are SST 90's. They also made an SST 70 which was the 7K version. Both are the early Super Tachs with the 270° needle sweep. The easiest way to tell is to remove the tach head from the cup and look at the back of the unit. If it has a black bakelite back and a red metal tag on the bottom, it requires a transmitter. In fact, that's what the tag says........ "requires an EB-9A transmitter", or something to that effect. I'll try to post some photos shortly if this stinkin' computer doesn't crash again!
Steve,
For now, the unit in your pictures is the later transistorized style and DOES NOT require a transmitter. This may also explain the difference between the Blue stripe and the Green stripe.
(Both mine have green stripes.)