which of these things is not like the other?

I had the feeling a j109 was going bad, crazy tach and other issues. After searchin and askin I pulled them and one was alot larger than the "Bed" on the side of the dizzy and significantly larger than the replacement.

Somebody please explain this to me I'm still kinda new to rotary. Why was it bigger, why would the last guy do this, where did the bigger one come from, Why Why Why?????

 

The larger ignitor is off of a 1980 model, i forget the ignitor name off the top of my head.

 

It's a J105, from a 1980, yep. The 1980's had the ignitors on a box on the fender, rather than on the dizzy.