NEW SWS CHEVY ALUMINUM BELLHOUSING, GM 621 3899621 REPLACEMENT FOR SBC & BBC FOR 11" MANUAL CLUTCH APPLICATIONS Brand New Southwest Speed Chevy Aluminum Bellhousing to fit 11" Clutches (SWS Part # 650-3975) &gt; This bellhousing is a replica to the GM 3899621 &gt; This Southwest Speed 11" Performance Cast Aluminum Bellhousing is a reproduction of the original 3899621 bellhousing used on GM models with Big Block and Small Block engines equipped with an 11" clutch &gt; This performance aluminum bellhousing does not have the GM Part # 3899621 casting number but will look, fit, and perform just like original Features: | * Replaces GM Part # 3899621 | * Cast Aluminum Housing | * Works with GM transmissions with a 4.675" O.D. Bearing Retainer | * Clears 168 tooth 14" Flywheels with factory 11" clutch discs | * 1/2"-13 tapped hole for z-bar manual clutch linkage, if needed. | * Fits ALL Small Block and Big Block Chevrolet engines regardless of factory clutch size Fits: &gt; 1964 - 1988 Chevy Chevelle, Malibu, Monte Carlo &gt; 1959 - 1987 Chevy El Camino &gt; 1959 - 1988 Chevy Impala, Caprice, Bel Air, Biscayne, Brookwood, Kingswood, Nomad, Sedan Delivery &gt; 1963 - 1981 Chevy Corvette &gt; 1967 - 1981 Chevy Camaro &gt; 1968 - 1974 Chevy II, Nova &gt; With Manual Transmissions and 168 tooth Flywheel The bellhousing was used with 4 speed transmissions in 66 - 72 Chevelle, 66 - 81 Corvette, 67 - 72 Camaro, 68 - 72 Nova, and 64 - 81 Impala, but with any GM transmission that measures 4.675" and an 11" clutch, it will fit great in all of the additional applications shown above, as well as many different types of projects &gt; This will make it a snap to get that big GM bellhousing in your muscle car or rod project This new Chevy high performance 11" style aluminum bellhousing was issued on Camaros, Chevelles, Impalas, Corvettes and Nova's with big block 396, 427, and 454 engines, as well as Yenko, Copo, and ZL1 and also small blocks like 302, 327, 350 and 400 with the 168 tooth, 14" flywheels and 11" clutches, including Z28, Yenko, and Deuce models