My understanding from Arno's book is that he started the 1764's in 1974 and made less than 200 of them. Painted terra cotta and marron with a few made with chrome plating and laquered brass (unfinished look).
The book says he also did one for a customer with silver plating and gold accents. They were all sold without a motor and sold for $375 ( quite a bit in 1974 dollars ).
I have a brass one. Previous owner added a motor. Seized when I purchased, but back on the rails now!