RMills944

Here's what some of the off-road guys that build tube-frame buggys recommend:
http://www.pirate4x4.com/forum/archi.../t-166034.html
http://www.pirate4x4.com/forum/archi.../t-283886.html

My brother has the Miller 175 220v, and it's an awesome machine. I'd recommend getting a 220 if you don't mind wiring a garage for it. I'd also recommend going with something decent as you don't want to keep messing with it. You want something you can pick up and it'll just work.

Geo

What size is it?

Unless it's a 210 or larger either you're welding a lot of thin stuff or you're not welding for more than a few seconds at a time.

I'll reiterate, pay attention to duty cycle.

Welding a sand rail will require welding 0.95 tubing or thicker and some of the welds will take more than a few seconds. A 185 would probably suffice, but I wouldn't go any smaller.

88BlueTSiQuest

I've got a pre-Lincoln Marquette body shop welder. 220v 180amp. Just to play around with it, I've used it to burn through 1/4" plate steel, and it's never heated up or piddled out on me.

I'd say in shopping for a MIG, look for something with several wire speed and heat settings. I believe my dials are from 0-10 infinate, allowing you to fine tune your settings.

Also look for the ability to hook up a spool gun, most newer welders have this.