Questions after gear install

[buckinwild]

I installed my own gears because there are no reputable shops close to where I live, I've already had experiences with the only two that would even try to install gears, one didn't even shim the pinion and I'll keep it short but that was a bad experience. The 2nd shop I went to was better but the gears still had whine to em' . Anyway long to short I figured I am inclined enough to do as good as anyone in this town. Alright this is the situation. Setting pinion depth was acheived by measuring the original shim and pinion thickness and doing the same to the pinion I was putting in, so the overall thickness was the same, I combined a .010 with a .014 to make shim thickness .024. Now backlash was time consuming, I know the window for this is .008 to .015 but no matter how we arranged the shims .006 to .018 was as close as we could get. When I installed the original spacers that came with the car, backlash was .003. Anyway I went with .006 for backlash and hoped for the best. As for bearing preload I just tightened the pinion nut until the yoke and other pieces seated the way they were before the swap and compared turning it by hand before and after and checked to make sure there was no back and forth play. Anyway, I have a slight whine only when I coast, none when I accelerate, and its most noticeable in 4th gear, 3rd will at clutch engagement during a downshift coast but only for a split second. Can't hear it in 1st, 2nd, or 5th under any condition and I was just wondering if changing backlash to the high side or reshiming the pinion a tad thicker would cure it.