Revolutionary aluminum driveshafts are built using a two part, weld-free process that eliminates distortion and loss of heat treating strength. Hard coat anodized, forged aluminum end yokes are interference fit in O. D. ground, 3. 0" x . 120" aluminum tube and then reinforced with six monobolt fasteners. All driveshafts include heavy duty 1310 Style U-joints and are computer balanced to less than 1/8 ounce per inch. Driveshafts do not include yoke. Quarter Master driveshafts feature unsurpassed strength and smooth, vibration free performance. Quality material selection, rigid tolerances, careful attention to detail during assembly and a balance spec to less than . 125 ounces per inch separate the best from the rest. Hardcoat anodized forged aluminum end yokes are interference fit to special O. D. ground 3. 0" x . 120" aerospace aluminum tube then reinforced with six Monobolt aircraft fasteners. These shafts weigh 40% less than their steel counterparts. Maximum center-to-center length is 51-3/16". Procedure for Measuring Shaft length:The most important dimension of your new aluminum drive shaft is the length. This length is expressed as the distance between the centers of the front and rear U-Joints. To arrive at this dimension, first raise the car off the ground, being very careful to insure that the normal vehicle weight is being supported by the rear suspension. (The suspension is not at full droop or unnecessarily compressed. )Take the slip yoke that the driveshaft will be assembled to and insert it all the way into the tailshaft housing of the transmission. Now pull it out 3/4" to 1". This will be the free play that all driveshafts need when the suspension moves through its full range of travel. Carefully measure the distance between the centers of the front and rear U-Joints.Double check the 3/4" to 1" free play in the slip yoke and measure again as we are not responsible for wrong measurements. This is the length for your new Quarter Master aluminum drive shaft. Round off this dimension to the nearest 1/4" increment.Pit Stop USA offers Quarter Master Aluminum Racing Drive Shaft - 39" 188390 at low everyday prices. Be sure to check out all of our products from Quarter Master including Quarter Master Aluminum Driveshafts.