Does anyone know what the difference is between the open diff s13 output shaft and the s14 Vlsd output shaft?

I am aware that the lock ring groove is in the wrong location, is there anything else? The reason why I am asking is, we have recently installed the old style kaaz lsd, which requires the use of 2 short side s14 vlsd output shafts. We did not have any available at the time and instead, used 2 short side s13 open diff output shafts. The vehicle is drivable but is making some clunking noises, aside from the normal diff clunking; we were wondering if maybe the noise was coming from the output shafts? We had the car up on the dyno today and could not seem to locate the source of the noise. We noticed the output shaft had some play. I know, just buy the s14 output shafts, though I am trying to save this guy some money.

Because of our location, we could not find anyone who has experience in this area any help would be greatly appreciated.

http://www.redline808.com