Are you just taking one out and puting the same type back??? If yes the easy and sure way would be to remove the cap so you can see the rotor. bump the engine over till the rotor faces the fire wall. put a mark on the fire wall at that point. remove the dist. hold down bolt and clamp. Pull out the dist. install the new on in reverse order making sure to get rotor in the same place. The dist. will probably go down to within a 1/4" of all the way. that means the oil pump is not lined up BUT the timing is right.If you can gave a friend bump the starter while you hold the dist. down it will rotate and drop in place. replace the hold down clamp and bolt snug it down put cap and wires back on Start engine and set timing. It realy is that easy.