the p2s are also 5 3/4 but when u take the magnet cover they get trimmed down by quit alot. example the p2 12" the mounting depth was 6 3/8 after the cover was removed it went to 5 3/4. the diameter was 7 1/2 after it was 5, and the circumference was 25 after it went to 16.
ps, i called Obcon...