Dodge truck 3.9 engine ECU 53008923 Up for Sale is a Working, in excellent condition dodge truck engine ECU. My list shows this works with most 1991 3.9 Liter automatic transmission federal emission Trucks. Part number listed at the top or in the large pictures. Check the part number to be sure this is right for your Truck. If you priced one of these new, you probably ran away screaming... Mine is a bargain price. This unit is a rebuilt unit - only run about 1 year before this truck was in a minor front end collision. No damage to the drive system or this unit, this truck still ran fine when we removed itThese are very hard to find in good working condition. This unit was runtested & is functional, and offers a 30 day warranty. Please be sure to double check the part number off your original unit before buying. A defective unit is one of the most common no start or random stalling problems with these trucks. They can also be the cause of erroneous check engine lights, cold or hot start problems, or idle control malfunctions. If yours does not have problems, keep an extra ECU in the trunk, you might some day be glad you did... These units are very expensive to buy new. Thanks for looking!