Dan, I've spent the thick end of a decade trying to work this out, by staring at around 2,000 photographs...
Is there a site that I can go to, or help from the forum members for detailing what the design differences are from the Mk1 Cooper 500 to the last 500 that they produced.
There are four basic body shapes:
- Prototypes (both subtly different)
- Early-period: 1948 Mk II - 1950 Mk IV + the 1950 Lightweight: Slab sides & upright shape
- Mid-period: 1951 Mk V - 1953 Mk VII: Pontoon sides, sloped nose & tail
- Late-period: 1954 Mk VIII - 1959 Mk XIII: Cigar tube body
but with a myriad of small developments through model types (and sometimes within).
Generally, there were LWB versions with an extension of 1-3" in the engine bay to take the JAP Twin. I believe early models (Mk II and perhaps Mk III) actually just moved the seat forward (still trying to find a source). BTW, I believe Terry Wright asked owners to measure their chassis to help resolve this once and for all - rumour has it that no two cars matched anyway!
The other major change was for the 1952 Mk VI. The Mk V was basically the same structure as the Mk IV, with channel-section ladder frame. The Mk VI had the same streamlined shape as the Mk V, but underneath was a twin-tube chassis. Of course, for the Mk VIII, the "bent-tube" chassis was introduced with the new bodyshape.
Contemporary reports often mention details like brake cylinders, engine position, suspension, etc., but there are often subtle, unmentioned changes. Some give you visual clues (with the right angle, and presuming the car wasn't upgraded by the factory or privately). However, bits still pass you by - I had missed the whole wheel-style issue, and I'm still looking for a good cockpit shot of a verified Mk X to confirm tacho position.