If there are no numbers on it it's going to be hard without pics. There are four possibilities, Autolite, Prestolite, Mallory, and Mercruiser. The numbers would be on a plate or stamped into the housing.
Let us know where you find it I am looking to change over to electronic as well.....I THINK i have a prestolite since it is a screw on cap, others appear to be clip ons....
does your distributor have the screw down cap, if so let me know what conversion kit you ended up with and how it works.........
I have tried 3 so far from Parts store and they get me the wrong one every time.....from wrong part in correct box....to something totally non related.