28/29 rad shells compatibility

[Mike Costigan]

That's good to know the early shorter rad shell finishes when the magneto finishes... 

Well, almost! In fact the raised nickel-plated shells were introduced in August 1928 at A6-9330 (chassis 67024), the first coil engine was fitted to A7-1280 (68814, engine 69000) and not standardised until A7-1569 (69135). The RK (wide-door saloon style) was not standardised until A7-6400, so there were both mag-engined and coil-engined R saloons with the larger radiator.