The 1050 Dominator on the right is physically larger than the 950 version on the left. The black anodized metering blocks are a quick way to identify the Ultra HP carbs. The Holley part number is 80672 for the 1050 carb and 80676 for the 950 version. Keep in mind, if you're going to use the 4500-style carburetor on an intake designed for a 4150, you'll need an adaptor. This also will create hood-clearance issues.