How do you tell the difference between a 3.89 and 4.22 differential?

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SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="606" HSPACE="0" VSPACE="0"></tD> </tR> <tR> </tR> </TABLE></div> <bR> <div> How do you tell the difference between  a 3.89 and 4.22 differential?</div> <bR> <div> From the outside, turn the diff input flange with someone counting</div> <div> axles revs.</div> <div> Block one of the rear wheels "This turns the unblocked axle at double</div> <div> speed".</div> <bR> <div> turn the input flange 5 times.</div> <bR> <div> if the axles turn 2.57 revs, it be a 3.89.</div> <div> if the axles turn 2.37 revs, it be a 4.22</div> <bR> <div> From the inside "looking at the crown gear" there is</div> <div> a stamped number on the outside of the crown wheel.</div> <bR> <div> The number stamped on the 3.70 is 37X10 (37/10=3.7)</div> <div> 37 crown teeth, 10 pinion teeth.</div> <bR> <div> The number stamped on the 3.89 is 35X9 (35/9=3.889)</div> <div> 35 crown teeth, 9 pinion teeth.</div> <bR> <div> The number stamped on the 4.22 is 38X9 (38/9=4.222)</div> <div> 38 crown teeth, 9 pinion teeth.</div> <bR> <div> The number stamped on the 4.55 is 41X9 (41/9=4.555)</div> <div> 41 crown teeth, 9 pinion teeth.</div> <bR> <div> The carriers, are never marked, and the 3.70, 3.89 and 4.22 gears</div> <div> could be in the Alpine carrier, and you would never know it.</div> <div> This diff unit has the input flange low towards the ground.</div> <bR> <div> The 4.55 carrier looks different than the true alpine carrier, but</div> <div> fits the alpine case, provided the proper axles were used.</div> <div> This diff unit has the input flange set higher at about the axle line. </div> </td> </tr></table></body>