Quote Originally Posted by content22207 View Post
Nonsense. In Ford's case at least, taller distributor caps are an illusion -- the cap itself is the same height -- there's an adapter ring between it and the distributor body to house the magnetic pickup. Diameter of course was unchanged (a 1969 breaker point cap is the same diameter as a 1979 breakerless cap for the same engine).
Not true. The breakerless caps are significantly larger. It is true that an adapter ring was used since the aluminum distributor housing is basically unchanged. See image below.

IMG_1292.jpg

I'm in the middle of gathering parts for a duraspark swap on my '66 Mustang. The cap on the left is form the duraspark distributor from a '77 302 Mustang that I plan on using. The cap on the right is the original Ford points cap. Notice the size difference.