What was the difference between the two frames? Geometry? Mild steel or Chro-mo? Same time frame or which one came first? Was it the Racer X or the Super X?

i believe they only made one model. i've only seen racer x frames with super x frame decals even in mongoose catalogs. production was 76-78, not sure if they made any in 79? i don't know how to post pictures, otherwise i would. post your pictures of your racer x, always love to see racer x.

The 1978 Super-X by Racer's Eng.

The '79 Mongose catalog (which shows pics of the '78 bikes) lists it as a Racer-X, with the decals labeled Super-X. It also states it's a tri-moly frame, available in red, blue, or nickel.