Smog Pump Eliminator...

I have used an 84.5'' on one car and an 85'' on the other. I Think the condition of the tensioner makes a difference. Most people just buy a couple in that range and return the one that doesn't fit. You will also have to reroute the belt a bit from stock. There is a great diagram of this that floats around this site, but I am at work and don't have it on this computer. But if you do a search for "short belt" or something similar I bet you find it.
 
I think the reason they say: "works with all supercharged applications" is because you can't run a short belt (84.5) if you have a blower. So basically, the only time you need to order an eliminator kit is if you plan on running a supercharger. Can anyone else confirm this?