I am looking to replace the OEM speakers in the front doors of my 2006 E-150. Does anyone know what size they are? Round or oval? (So I don't have to take the door panel off to measure them)

 

They are 6x8. Most car stereo companies have speakers that fit these openings - my favorites are Pioneer.

 

Take a look at Crutchfield's site. They'll show you the many aftermarket speakers to fit the doors, mid and rear.

 

They are 6x8 in all 6 speaker locations. And 5x7 speakers will also usually fit.

I prefer the sound of round speakers, so I put some 6.5" JL Audio coax speakers in the front doors. To make the speakers fit I made some rough adapter plates real quick from a thin kitchen cutting board. I screwed the plate to the 4 stock screw holes, and then screwed the speaker to the adapter plate. I used a black plastic cutting board because its cheap and it won't degrade like a piece of wood would. I mounted the crossovers behind the armrest area of the door panel. Sounds much better than stock.

Be sure to watch the polarity on the stock speaker wires. Having reverse polarity will kill your bass. The + positive wire is the wire closest to the little tab on the disconnect plug.