Get an alignment done to it. It is cheap and it will probably solve the pulling to the right. Like you said he did the work to it himself and he most likely didn't have it aligned.
1997 grand cherokee 4.0L, forest green, 3" skyjacker, 1" spacers, adj. front track bar, skyjacker sway bar dissconnects, procomp steering stabilizer, 31" super swamper LTB's, safari bar w/ 2 KC's, custom roof rack w/ 2 KC's, tow hooks front and back, CB, dynomax turbo muffler, custom K&N filter charger, 2 12" sony explode subs.