Yorks (particularly the 10 cfm type, model 210) have the biggest output and have an internally separated oiling system. They are pretty sturdy, long lasting and usually come with a V-belt pulley. Because of the size and the recommended vertical mounting orientation making it fit can be a challenge.
The other type is the rotary type (Sanden and others) that is also pretty good but it relies on the AC coolant for lubrication and comes with serpentine pulley. If you use it as an air comp. you're advised to fab in an air oiling system to provide lubrication. Some says that with occasional use it's ok just to squirt some lube in the air line and forget it.
Which one you chose is dependent on other factors too. In my case I wanted a rotary type w/serpentine pulley because I don't have AC and it'll fit at the AC location using a longer serp. belt. I also plan to add a second alternator for an onboard welder that will have a v-belt pulley and it will be driven by a combo serp./v-belt pulley off the stock alternator. You could also do it the other way around I suppose, it just depends. I got the rotary for $40, the yard wanted $80 for the 10 cfm York! [img]/wwwthreads_images/icons/crazy.gif[/img] Hope this helps.
'91 YJ,I-6,2.5" lift,Boomerangs,33s,D30,D35c,Lock-Rights F&R