Driveshaft lengths all mopars

Yes I understand that 73 chgrs didnt come from factory with 383,but any 73 chgr that had 727--8 3/4 rears and v-8's 318-340-400-440 would have the same length driveshaft..this paticular car has a 68 383-727--8 3/4 rear,nothing from factory has been changed in suspension/motor mounts etc..unlike my dart which rearend was moved so different driveshaft was fabbed...I would've thought this info would be so scarce,He called me last nite and says it measures out at 51 1/2" length but I dont know if he allowed for any movement in trans yoke or not,so I am going to have him re-measure today,the only one close that I have measures 50 3/4" so he may have to have one cut down and rebalanced for his car...thanks to all for your help....