Having worked on drive shafts "along time ago" in a NAPA machine shop, I would never assume a factory shaft is REALLY straight and balanced let alone a 38 year old shaft. If you have a dent(even a small dent) in the shaft definitely take it to a drive line shop and have it looked at. Depending on the size of the dent the driveline may need new tubing. With the horsepower and speed in some of these cars it makes alot of sense to run a balanced and straight shaft.
FYI, I just took my driveline in and had it balanced and straighted. If I remember correctly it was "out of straight" something like .050. I may not feel the difference next summer but at least I know the drive line is not causing problems. I THINK I HAD TOO MUCH FUN LAST SUMMER.!!!!!
