Does anyone know how to ID

F16, F16 CR both come with either 3.55 or 3.72 Final drive

F20, F20 CR both come with either3.4?, 3.5 or 3.7 Final drive

VX reckoned all the "CR" boxes were in the sport models, but with all this swapping/UG going on it can't be relied on. VX also said 2 letter code such as AF should be on the box, I could find nothing on the 3 boxes I have. Anyone have a bolt on plate with 2 letter codes on their boxes??

Any other clever ways of ID????

I need a F16 CR with 3.72 for Knockhill track days.