What is the difference between an rd690 and a rd688? I have looked around and there are various answers to this....
Looks to me like a number
They have different engines. the last two numbers designate engine
Thanks miro! Does anyone know if there is different variations in E6 or E7 motors? (maxidyne, econodyne? etc) Looking for a mid to late nineties Mack dump truck. Whats the best setup?