225 to 318 question

The shaft will have to be shortend for both the 518 and 8.75 so try to install both trans and rear axle at the same time to keep from cutting the driveshaft twice. The 518 (and 500) takes the same yoke as a 727, so that is easy to find in your small u joint size. Alot of the factory drive shafts have an inside liner mounted in rubber that gets in the way if the shaft is shortend more than 2 or 3 inches. You can not tell untill you cut the shaft if it has one. If you change the trans and rear end, your shaft will be shortend well more than that.