im sure when my engine was built we used Kings bearings that were for rb26 because i said use ACL and he said kings bearing where better but i will have to ask them in two weeks when go in for anther oil change. i also found that every part i brought for my built was machined at the machine shop in some way ie, PAR rods were not perfect, Mahl pistons had a 21.1mm pins and the crank was grub screwed and everythink was balance