I have a 1976 Chevy K10 with a 350 and no spark?

[Shade.Tree29]

It has happened now for the third time. The last two times over three months have replaced distributor cap, rotor, coil, and pin.
Not all the stuff twice. Cap and pin was the first thing replaced, then a couple of weeks ago replaced rotor and coil.

 

[Herbert J]

Replace the rotor again.