I have a set of focal 5.25 components I'm about to install in my '99 f-250. Have to wait till after Christmas so the wife doesn't know I bought them for myself this close to Christmas . The stock speaker hole is supposed to accept both 5x7 or 6x8 speakers.
I bought schoshe 6x8 to 5.25 plastic adapter rings, but these things seem pretty "rinky dink". The hole in the middle is also alllllmost too large to seal up behind the 5.25 midrange driver. It's pretty much the same diameter as that of the driver.
I'm concerned about not getting the full quality from my speakers if these things don't seal up behind the 5.25 woofer properly. I'd be better off to purchase some 1/4 mdf and make my own adapters, wouldn't I?