I've read the other posts, and while they all have merit, no one tied the whole process together. The distributor drive is offset and can only engage the drive gear in one position, so even if the motor has been turned (compression test?), the distributor will be in proper relation when it is set back in place. The only danger with removing the aluminum distributor mount is that the drive gear could get lifted out of position while cranking--but that's a remote possibility. Take a screwdriver and push down on the gear to be sure. I've always serviced distributors on the bench, but remove it by loosening the pinch bolt. Assuming things have been kept original number 1 should face forward, angled towards the block -- 3,4,and 2 counterclockwise from 1--you'll find a slash on the upper ridge of the distributor indicating number one. If your distributor has a vacuum unit it usually sits towards the firewall about a fingers width from the block.