So me personally - I had mine cut, metal put inside for strength and then welded back together and keeping the same threads, however 55 trucker cut the threads himself and I think this approach is way easier/better than cutting and welding.
Saying this, if I was to need to replace this one, I'd 100% buy the proper size die to do it myself. no reason to take to a machine shop if you're comfortable with a using a die. 55 trucker has outlined the size/pitch thread die needed in this thread here.