I have always hear that these early 60 year skirts were different then the standard car. the have been describes as longer. yesterday I got the opportunity to wake up and see what the difference is. we have a NOS set of 63 caddy skirts for Brendon's 63 high top. the lefts side fit well and went on and off easily. but the right side has some damage and the quarter was bad so I have be fighting getting it to lock in. got it finally and in the process I have discovered that all then did was grind off a section of the standard skirt to make the commercial chassis skirt. this was done to accommodate the wider with of the rear end. it's just enough to clear the side wall. so for the 63 model you can use the standard skirt if you modify it like this. I would suspect the rest of the years are the same also. but can't confirm that.