From my I.H. contact. The difference seem to be more color combinations available on the Sundance I.
Sundance I
Available on all Loadstar models, metal and fiberglass hood.
“The paint scheme for the cab and hood was essentially white with a contrasting color used for most of the cab and the top of the hood.
The contrasting colors offered were Fire Orange, Solar Yellow, Tamarak Bronze or Terra Cotta, and the frame and wheels were painted to match the darker color.
The trim package included a bright windshield molding, west coast mirrors, a rubber running board step, and a chromed bumper, a premium seat, vinyl-covered dash, and engine-turned Instrument panel, with matching glove box door .
Sundance II
Available on all Loadstar models, metal and fiberglass hood.
“It involved a white cab roof and hood, medium metallic brown lower panels, an orange stripe on the upper body, and orange paint on the chassis, running board and wheel spokes.
The wheel rims where gray, and the grille and bumper were painted silver.”
Sundance option was available to at least 1978 I'm told. Paul