Frames: S4 vs S1 differences

[wbmoore]

I've inherited a S4 frame....I'm told it is from a Sprint. Are there differences between this and a S1 frame ?

[types26/36]

The S1/2 frame (chassis) had more caster built into the front geometry, it was reduced with the S3/4 frame probably to make the steering lighter in turns.
I also believe the S3/4 frame has a few more gussets (strengthening around the front towers to main frame)
I dont think there is any reason why either frame cant be used with either body style as I believe the basic measurements are the same.
Others may know of some other differences so happy to be corrected.