I use the Ratech solid pinion spacer. Very nice to use during new gear set up as you can dial in your pinion shim pre-load the same each time you change a shim. My thoughts on the pinion tool are, it will get you close but there is no substitute for running a pattern using marking compound, so I never use the tool. Back to the solid shim spacer, I have found the parallel surfaces that bank against the pinion bearings are not parallel. sometimes off as much as .004" so I square the two sides to each other on the lathe to .0005". Just check it before you install, otherwise bearings cock in the races. Instructions say pinion nut 125ftlbs, I prefer near 200ftlbs with a healthy dose of red Loctite on a new pinion nut, and smidge of sealer on the inside splines of the yoke to prevent oil leaks.