For a 68, What is the difference between them? I know the RS has a hole cut out for the bellcank but is that the only difference? I'm especially interested in the LH which holds the vacuum tank. Is there anything on the RS LH that is not on the non-RS?
I see that Rick's has both but many of the other suppliers only have a non-RS and they say can be easily modified to RS. Other than cutting that hole for the bellcrank, what else woudl I have to do if I pick up a non-RS to use on my RS?

The mount for the headlight buckets sits further back on the RS fenders. You can buy that mount and weld it on if you are going to paint the fender.

I thought the headlight mount was on the fender. I am talking about the fenderwell or skirt or inner fender. My outer fenders are in good shape.

Oh fenderwells....never saw the "wells" part. I didn't know there was a difference with the 67's RS/nonRS fenderwells. Maybe the 68 headlight vacuum system needs mounting holes. On 67's I don't think there is a difference. I also don't recall noticing any differences from the 67 and 68 RS cars I've owned.

Theres no difference in the sheet metal of the inner fenderwells. The RS's just have more holes drilled in them to allow the belcrank to pass thru as well as attachment points for the various additional brackets that the RS headlights and vacuum actuators use.

The fender cans are the same and they all have dimples or "pip marks" in the positions corresponding to the places where the holes for the RS parts get bolted in.