65 GTO Electro-Tech rear speaker installed with modded Ames enclosure
 

I bought new Electro-Tech front and rear speakers from www.turnswitch.com, since Ames had theirs on backorder for a long time. These are correct 10 ohm speakers with higher-sensitivity neodymium "super magnets" but the housing is not stock, like the Ames repros. I modified the correct Ames rear speaker enclosure to work with this speaker housing.

Measurements I took for future reference:

Stock enclosure magnet "grips" are .900" wide, you need to put a .630" cutout in the middle of the one facing the enclosure opening (leaves two thin .135" "fingers" on that one). You need to bend the metal clips open to where it will "grip" a 3.42" opening around the new speaker housing. Then I bent the tips back inward so they would hook on the speaker housing when installed.

Ideally this looks close to factory correct. Pictures for reference.