Fits All SB Chrysler Fits All BB Chrysler This damper is supplied as a neutral balance damper with two counterweights with the damper. 1972-'78 383 & 400, '71 383 2-bbl and '74-'78 440 (cast crank engines only) use counterweight #91015. 1970-'71 440 6-bbl and the 1971 High Performance 440 use counterweight #91016. All other Chrysler big blocks require no weight. The damper also has two extra TDC marks for either the 426 street or race Hemi. To fit the Hemi, spacer #81013 is also required. This damper will not work on the 331, 354, or 392 early Hemi but basically fits all other big block Chrysler engines including the 351, 361, 383, 400, 413, 426 and 440. Complete instructions are included with the damper.