The early 800's (1963 gold & white) used the Wisc S7D engines.
The later 800's (1964-1965 brown & white) used the Wisc S8D engines.
HOWEVER, there was a Bolens Letter issued to dealers explaining that some 800's were shipped from the factory with an S7D in place of the S8D.
I don't remember the reason why - possibly a shortage of S8D's. ...These tractors were identified with a "-7" suffix added after the tractor model number.
Also, Bolens production did not always match what was shown in the brochures. ...Even production info published by Bolens has numerous errors.
I, too, worked in a Bolens dealership while these tractors were being sold new. ...I do not recall ever seeing a 1964 or 1965 Bolens 800 with the S7D installed at the factory. ....That is not to say that a different dealership (or distributor)could not have received a batch of the 800's equipped with the S7D.