A $450 core charge is included in the price of this Valve Body. The core charge is fully refundable upon return of your core. Please call for details. Modified, tuned and tested BD’s Allison 1000 valve body prevents clutch slippage! New trim valves are installed to match the mainline pressure giving more clamping force on the clutch plates. Surfaces are lapped to ensure no internal leakage which can cause shift irregularities, clutch pack pressure loss and lube oil loss. All of these issues lead to premature failure of internal transmission components, error codes lighting up the dash and driver dissatisfaction that BDs valve body will help prevent. The Allison exchange valve body saves installation time over installing a shift kit. In less then 2 hours you can be back on the road with confidence your transmission is holding up to the loads you are pulling or the increases in power produced by installed performance boxes and tuners. The Allison valve body is a must for trucks towing moderate loads or racers who have increases of 90rwhp to 120rwhp. For heavy haulers or extreme power, we suggest further transmission modifications or exchange out with one of our heavy duty transmissions and convertors.