Has anyone converted the rear speakers of a 88-93 chevy truck to 6x9s? Im interested in this project but i think it would have to be all custom with holes cut and all that...

what kinda truck?

89 chevy 2500

you wont have a deep enough area... unless you get some really shallow 6x9s. But if their is a will; their is a way. Personally I would just get a sub. and some 4x6 Kapa's from Infinity. with a good deck (Pioneer 6000 sereis+) a bit more; but it will sound wonderful!