many people wonder what the difference between these manifolds is. the 7053 gm was used from 80 - 85 on z28 / firebird, monte carlo ss, caprice, some trucks, etc. it is essentially an aluminum replacement for the cast iron 4v manifold. it has E.G.R. but no provision for hot air choke. both manifolds are for spread-bore carbs. a visual inspection of the two side by side shows that both have similar placement of O.E.M. fittings etc. the 7053 has a 4 hole plenum and the edelbrock a split plenum. the gm has the exhaust cross-over heat sheild, the 2101 does not. the 2101 has provision for hot air choke but not E.G.R. the runners on the edelbrock appear to be a better design than the gm unit. the plenum floor and runners on the 7053 are quite rough whereas the 2101 are reasonably smooth. i would think that you would not be able to notice any difference in performance between the factory cast iron and the 7053 but the aluminum will dissipate heat better and give you E.G.R.if you need it. judging by the visual comparison alone i feel that with the 2101 you would notice some improvement in performance. i bought both manifolds quite cheap from kijiji. also both will provide hood clearance without using a drop base air cleaner. doug.