Hi all, I need to replace the fan clutch on my 90 K-5, I want to use a Hayden # 2734 Heavy duty clutch from Kragen Autoparts but when I looked it up on the net it said the following: "Heavy Duty Thermal Fan Clutch: C.C.W.; w/A.C.; w/3.42 or 3.08 or 2.73 or Lower Rr. Axle Ratio" What the hell does axle ratio have to do with a fan clutch? Dan..