Hi Jerry,
Bit more info on trap door...
The Pohlman shot of the new trap door is 20318, part of a photoshoot prior to the 11th of May 1954 when these shots were filed.
Obviously, not done in the eng dept the day before...
In my view, that's not that late not to be seen on a 54 model, up to August/September...
I also think the clamour for a trap door was way more vocal from the race community than the dealers, the race guys had spare gear ratios to fit in the grass and long delays to fit them due to case splitting... But new trap door race cases were named -52RA rather than with the year, so no proof as such.
I'm pretty confident the trap door was 1st made available on the KR in early 54 and then found its way on the street.
Patrick