Rockauto sells companies I’ve never heard of engines . Oreilly and the like typically sell Jasper , I have installed hundreds of Jasper long blocks . I’m not going to go into a full bore bash fest but these big reman companies regularly send out highly repaired cylinder heads ( multiple weld repairs from previous cracks etc ) that are well below spec. I’ve taken multiple heads from engines just out of Warranty to highly reputable shops only for them to call me and say “ you’ve got to come down here and see this it’s junk “ when I arrive theres often been several areas circled in paint marker and a story to go with it . They’re assembled with the cheapest gaskets , and parts money can buy with the loosest tolerances possible and shipped to you from a warehouse for a premium price . I wouldn’t buy a reman engine from any big company like that . It is common for loud and oil burning new engines . They also love to try and skate out on warranty work repayment . I always recommend finding a good used engine . There ARE great engine builders out there however 4.0s are very plentiful and hard to kill . Also when I mention cheap parts and gaskets .... let me explain real quick ... you might get one off brand silicone and gasket set one week and an entirely different one the next ... sometimes gaskets so cheap they’re not even torn out of their stamped print yet ... meaning you have to poke the holes out of the form yourself .