Generally
A distributor cap that only fits cars with 3 carburetors. 3 Carburetors were standard equipment on the Eldorado, but were available as an accessory for all other models, This distributor cap is very hard to come by and there is no new manufacture of it nowadays. But we have it in stock, not cheap but we have it!
Check that you really have a Tri Power, 3 carburettor original distributor, if you look at the pictures you will see that the small door for the switch tip adjustment sits right next to one of the mounting screws, it does not on a standard distributor. It is not uncommon for the distributor to be replaced because the cover is so hard to get hold of, the cover is in the middle between the screws so this cover does not fit.
There are many different names for these carburettor sets with 3 pcs 2 port Rochester carburettors, Cadillac called them Eldorado Engine (3 dual-barrel carburators) or "Q" Engine, other names are e.g. Six pac, Tri power, etc
