you want 180 machine if your welding on frames i have had 3 wire welders over the years what happened as i started to get in to more thicker steel i found out the limit of each machine i ended up with a miller 250X sold it as i tig every thing now with my 275 lincoln .some welders go in to spay transfer so welds may not look the same as others its more to the welders liking as the weld my be strong more or less to a point but you may want the row of dimes look were we you play with the welder to get that look . were fast and fill for some jobs were they want to keep all heat in the steel to get the best penetration pulling and pushing the weld also plays in seting or how the weld looks .i just tig every thing now as i not fabing much on car most of all the stuff i do can be on the bench but if need i have a thumb wheel on torch and 30 feet lead if i must