[Greg Reimer 7376]

Seemed to me back in the days when 12 bolts were the newest things,a .030"-.032" pinion shim was correct about 90%of the time.It was far more common to be able to reuse the original pinion shim than not.It didn't matter too often if the gears were 2.73's or 5.86's. With a drag race ratio or anything in the 4.56-6.14 ratios, there would be variation in whatever carrier bearing shim you needed far more often than the pinion bearing shim.It was also common to take out an open carrier and install a correct series positraction carrier reusing the gear set without having to start from scratch to determine the proper shim thicknesses. The vendor that GM used to supply the gears must have been very accurate as to quality control.When everything that rotates gets replaced as in a new rear axle assembly being built, it usually is pretty consistent as well. The 8.50" 10 bolt that came out in 1973 to replace the 12 bolt was fairly close as well. Sounds to me that what you describe was a problem with the new gears.