From what limited information is available, the chassis and body frame were all the same from the 1997 upgrades.
The reshaped ash frame and stainless bulkhead came first, which according to the dealer notice was July. The superform wings came towards the end of the year. The front crosshead was the same across the range at that time as far as I can tell from the evidence. The 4/4 still had a steering box as standard in '97 with an optional rack.
The crosshead was widened on the Plus 4 and Roadster from 2010.
Its so complex that the only way to be definitive would be to measure every car. The stainless bulkhead was common across the range from '97 and so its reasonable to assume they were all the same.
I didn't look at the pre 1997 cars because that has already been covered in earlier books.........
