Hi again Michael,

Your inclusion of the pic of your 14" twin rail Model 45, with a Kirby engine, has started me on some more research this morning.
What I have found is interesting. wink

Your 14" model number 450407 is mentioned in the 1974-1975 Model Range, with the 17" model number 450423 and the 20" model number 450431 all sporting Kirby-Tecumseh (Lauson) engines. See here...the illustration seems to indicate a solid deck 20" machine with the ying/yang catcher decal.
[Linked Image]

From this information, I think with some confidence, considering the manufacturing date of your Briggs engine on your twin rail 14" machine being 30th August 1975, that the change-over from solid engine deck to twin rail was very late 1975. That is allowing 3 months for delivery of the Briggs, from the USA.

We have been trying to nail down this time frame for many years and your machine may have solved the puzzle. wink
cheers2


Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member.
Kindest Regards, Darryl grin