The orientation of which end of the dual M/C feeds which end of the car depends on the source of the M/C. GM typically (but not always) fed the front brakes from the front of the dual M/C. so GM disk/drum M/Cs tend to have the larger reservoir in the front. Ford and Chrysler typically fed the front brakes from the back of the M/C, so the Fairmont M/C has the larger reservoir in the back. So long as the system is plumbed correctly, the brakes don’t care which of these M/C configurations is used. Interestingly, the M/C used on the Vega/Monza cars are disk/drum but have the same size reservoirs.