B&M TH400 Shift Improver Kit
Fits 1965 to 1987 GM Turbo-Hydramatic 400, 375 and 475 automatic transmissions. The B&M Shift Improver Kit the easiest way to get the stout performance you’ve always wanted out of your automatic transmission. You get two modes of performance to select from: Heavy Duty or Street Strip. It’s our least expensive and simplest to install kit.