[TR] Commission number verification

[Randall]

> There's a small chance that comparing the frame's Z-number 
> would give an approximate correspondence to the time period 
> of the purported commission number.  Z-numbers are, at best, 
> a loose guide to the general period of production of the 
> frame, based on the ongoing engineering changes at Sankey's.

You can also get an equally loose estimate by comparing the car to the list of production modifications.
https://drive.google.com/open?id=0B2H2NJt34OffZ2VJVlM3ekxfajA

Just for an example, if your car lacks the raised plinths under the hood & trunk hinges, then the body is from a pre-60K car.

-- Randall