Source - 1969 Ford factory
From 1969-1972, Ford
offered an underhood 2500-watt electrical generator mainly as an
option on the Contractor's Special, though it could be special ordered
on any F250-F350. Trucks would come with heavy-duty front springs and required a special inner fenderwell
for mounting, and shared the truck's fuel supply.
These Onan generators
are manufactured by Cummins, Inc. I'm attempting to track down some
detailed information on them, but until then, these pictures will have
"(The) Electric Power Pack, a
unique underhood 2500-watt generator set, provides regular household
power (110/120) right on your job for electrical tools and camping
equipment. Unit is driven by it's own one-cylinder, electric starting,
5.5 hp air-cooled engine."
Source - 1971 Ford factory literature