Over the years, I have owned both versions of the Holley 3 barrels, and ran them on my Fairmont. They ran great performancewise, but lacked some of the part throttle drivability of later Holleys. They were basically a 3310 780 Holley with the material between the 2 secondary butterfies of the baseplate and main body cut away, and a single, large oval secondary plate installed. They used a large angled vacuum secondary housing, similar to a Chevy or Mopar 3x2 barrel unit, although the length of the vac diagphram rod is different. As mentioned, the sec. diagphram is onbsolete, not sure about carb kit availability either now. They used a funky cable operated manual choke flap, with no choke tower. To tella 950 vs 1050 cfm 3 barrel, check the secondary venturi area. A 950 has 2 booster, like most other Holley 4 barrels, but a 1050 has 2 simple brass tubes, with no booster bell to get in the way. Kinda crude, but it did work well at WOT.