Motive Power Ring and Pinion Set

[8EL]

Received a new ring and pinion gear set from Tam's Model A Parts yesterday. This set is made in Italy and marketed by Motive Gear. The instructions sate to verify that the serial numbers on the ring and pinion match, as they are lapped to a final fit, and are not interchangeable as individual units. Also stated in the instructions is that the number on the pinion is the reference to to dimension from the axle center line and the face of the pinion. It goes on to say that this tolerance is to be held to not greater that +- .002".

Makes sense right?

The only numbers can be found that could be realized as unique to these two parts are hand written in electric pencil, and are unlegible. Secondly, there would have to be some sort of special fixture, not sure how it would work to be able to precisely measure from the axle center line to the pinion face on this type of unit. Reason being that the axle bearings that the measuring tool would need to reference are located in the bolt on axle housings. Once bolted on, there is no means to access any type of measuring device to make this reading. On salisbury and carrier type rear ends ample access is to be gotten through the removed rear cover plate or removed carrier.

So I called the Motive Power technical support help line given wit these instructions for clarification. After much too do, I was given a long rambling statement from the supplier of this part that they have no information on it and could be of no further assistance.

I will be calling their customer support department Monday to get to the bottom of this matter as this answer can not be considered acceptable.

What do you guys make of the situation? Anyone installed one of these gear sets?