2005 Grand Marquis GS, non-premium sound.

Its a 5x7 im sure

I believe they're 6x8's, all the way round. Or at least you can replace them with 6x8s.

Those in MY 2004 front doors are RocFos 6x8's, replacing the factory units. A tight fit because of the speaker magnet and the center cone support.

All whale body Panthers are 6x8 all around except '98 and maybe '99s that had the premium sound option and had 6x9 in the rear.

The limiting factor in the front doors is window clearance. The window comes pretty close to the rear of the magnet on even stock speakers, I had a set of JVCs that would rub the window every few times I opened it. I just put Rockford Fostgate Prime 6x8s in my '98's front doors to go with the Prime 6x9s I have had in the back of all 3 of my Panthers. They sound 100x better than stock even with the stock "Premium Sound" radio.

I swapped in four JBL/Ford 2-way speakers in place of the full range single 6x8's. Sound had too much high frequency without the subwoofer. The cheapo standard speaker is a much better match for stock head units especially for listening to crappy FM.

I agree 100% about the 2-way JBL speaker assemblies. They sound horrible without the sub. When I bought my Town Car the sub was blown, the cone was just kinda sitting there not attached to the rest of the speaker, and it sounded absolutely awful, way too tinny. I swapped the speakers for my RF 6x9 and JVC 6x8 and it was a lot better, but it sounded great once I fixed the sub. Its clear that the factory JBL setup was only ever supposed to work with a sub. Fast forward 4 years and those JVCs died and I reinstalled the original Ford/JBL assemblies in the doors and they actually sound pretty good now.

I have RockFos 6x8 3 ways all the way round and they work great.