I was in my '63 Ranchero ( 289/T-10 ) and lost all power the other day while traveling at about 70 mph. Turns out the roll pin that holds the distributor drive gear to the dizzy has sheared. The gear looks decent. No real crazy wear pattern at all. The drive dear on the cam looks fine. Even the sheared roll pin stayed where it should. Both pieces poking out of the gear and the rest of it still in the dizzy shaft. The oil pump drive is intact and spins the oil pump nice and smooth. The distributor has been in the car 10 years in three different engines with no prior issue. It just seems like one of those things. But, what else could have caused such an immediate failure of that pin?