Steve,
Good find! Is yours a tiller steer or steering wheel?
I found a 24S Deluxe (steering wheel) last week a couple hours away. I've looked it over and under and haven't seen a serial number yet. From what I've seen and read, the Deluxe model was only built in 1967. The 24S, tiller steer was built in 1964 and 1967.
There is very little information on the 24S and 24S Deluxe.
I'll copy and paste what I have.
Mike