View 6 Photos View 0 Videos Jacobsen 40644 Engine Brake for Cummins ISX12 $1,000 USD (GOOD USED) Jacob Front Assy Jake Brake for Cummins ISX12 Diesel Engine, for sale!!!! Jacob Part #: 40644; Cummins Part #: 4298971; Cummins Supersession Part #'s: 4330980, 4330249; Stock #:... ConditionUsedFits To Make(s)CumminsFits To Model(s)ISX12Part Number4298971Stock NumberJB1017 MLS Number13582979CategoryEngine Brakes / Jake Brakes Last Updated5/15/2025 LocationHialeah, FL, US Sold ByJJ Rebuilders Inc. (844) 385-___ SHOWNUMBERCall Seller Email Seller Save More Info