I replaced mine this Spring. The original speakers are 6-1/2" Sony XS-MP61 dual cone with a 5" diam cut out in the arch plate and 4 bolts on a 5-1/2" diam circle. The mylar cone is glued to a center cylinder. The cone fell off one of the arch speakers and became very garbled. I bought two Alpine shallow depth 6-1/2" marine rated speakers on-line from Crutchfield that I thought had about the same dimensions. The original Sony speakers had a cover grill that measures 6-1/2", but the speaker body is only 6-1/4". The Alpine speakers have a speaker body that is 6-1/2", but the grille cover is about 7" diam. The speakers fit the opening, but the mounting screw circle is larger and the grille overhangs the arch plate.
The same Sony speakers are used in the cabin and mine were still working well. So I swapped out the cabin speakers to the arch and mounted the new Alpine speakers in the cabin. The Alpine speakers sound much better than the Sony, but the old Sony cabin speakers work well on the arch.
Another suggestion. I bought two closed cell foam speaker mounting cups when I bought the Alpine speakers and used them for backing behind the arch speakers. They keep water from getting into the back of the speakers and greatly improved the sound quality.
Good Luck!
