LS engines run a long time with care. Several hundred thousands of miles, with very little work. So if u find a good used, well taken care of 5.3with 100k cheap then I would definitely think about it. I like the idea of having cash left over for repairs down the road such as the trans. Plus you may upgrade down the road, so it leaves less investment in the old truck. As far as the 6.2, depends on the year. So if your timing gear is the 24 not the 58 then a change of computer is required. Again that’s one of the big differences between gen 3 and gen 4 engines. You can find a shop to update the old computer but only if it’s the same generation of engines, otherwise if you find the 6.2 get the computer that goes with it. Stand alone custom systems are a pain, believe me. So if it would be me.... I would find a good quality 5.3 and replace it if I had to, if not check your compression, if it’s good, replace your current oil pump and fix just what’s needed. Save up for and newer truck if your able to purchase down the road. That’s my take, hope it helps.
