Moore placed the Ratech tool in the housing as shown, using his left hand to hold the tool in place over the pinion while it rested on the carrier bearing saddle. Then, with his right hand, he used a dial caliper to measure from the tool face through to the bottom of the carrier saddle. This requires some finesse because the end of the caliper is flat but placed against a round saddle. Greater accuracy can be obtained by chamfering the square edges of the dial caliper plunger. The depth measured with the dial caliper was 0.596 inch. Using the Ratech reference 3.391 number stamped in the face of the tool, we subtracted the 0.596 from the 3.391 and came up with a pinion depth of 2.795. The T&D tool established the pinion depth at 2.801, which means the Ratech tool was only 0.006 inch off the T&D measurement—close enough to make it a good working number.