1969 Bronson Sportster from the pilot movie (filmed in Oct./Nov. 1968):

Stock '70 XLH from Jan 70 Cycle Guide.
Looks exactly like the Primary Cover on the Bronson Sportster:

Bronson Sportster from the time of the episodes (Jan. '70 Cycle World).
The Primary Cover clearly isn't ribbed, as it is in the '69 and '70 Sportsters:

Bronson Sportster from the fifth episode, filmed in late spring or summer of 1969 (photo'd off the tv). Again, no ribs on the cover: