I drive a 1999 F-350 Crew Cab. I just finished installing CS-AT1100 fusion active bass tube. I went and showed my dad and he turned the bass all the way up in the regular truck speakers and ended up blowing the speakers in about two seconds, so now I have to fix those but before I start anything I just want to know what the standard speaker sizes are. I believe they are 6" x 8" but I'm not sure.
and Greg, are you saying you got the fusion 6 x8s? That is the kind of speakers I would want to get so I can keep the fusion speakers through out the truck
No, I purchased a set of Kenwood speakers from Crutchfield and they were a direct bolt in replacement (front and rear). The mounting holes lined up and there were no modifications required to make them fit. They even shipped with the special wiring harness connectors so the speakers would plug right into the Ford wiring. If I remember correctly, they even send some installation instructions with photos so the install was pretty easy. Took about 30 minutes.
I am not familiar with the Fusion brand of speakers, they may have a larger magnet base and could have some clearance issues. Perhaps you can look at the link I provided and copy down all the dimensions and cross reference to the brand you are looking at and see if they are the same basic size. If so, then they will probably fit.