I think you are not getting any response to your question because you have left out some info.
-Type of steel you are welding? - What positions are you generally going to be welding in? - What are you welding on the truck? - Your skill level?
Right off the bat I would suggest using basic 7018 electrodes for structural work. Once again there are different techniques depending on a number of variables that have to be considered
sorry about that the welding is to cut and shorten the frame, it probably high tensile steel, the welding will be vertical at a 45 deg. and I have average weilding skills. Thanks Jim