Just to add an international flavour to this fascinating thread, here's a pic I took of 4 'birds on the seafront in my hometown of Brighton in Sussex, England in about 1983, at one of the earliest MMA UK meets. At the time, this represented about 50% of the wing cars in the UK, but several others have visited these shores since then.

The red car nearest the camera has been restored back to its correct Petty blue in the last year, having spent almost 20 years dismantled in boxes scattered around the UK (well done Pete!)