well a while ago i picked up two systems..one out of a mid 70's truck(with a 350) and system out of an 80s truck(with a 454) (i have a 75 blazer) then i started to put one of them in my truck. but now the high pressure and low pressure lines to the system seem to be switched in position. one now fits the left hole and the other now fits the hole on the right. i have to cross my original lines inorder to make them fit. I dont know if this is right, i havent read anywhere that the lines are crossed..sorry hard to explain...both systems are same with hole size positions.. i'll try to take pictures of what i'm talking about...but right now easter bunny is calling.