I have a '81 Vette and I need front speakers. Before I start taking things apart, am I limited to a size for front in dash speahers?

where do you want to put them? In a small car, why does it matter if you have speakers in the dash? They make little tiny speakers now that sound great- if you have to have them in front of you, keep the car as stock looking as possible- don't go cuttin, and butcherin'- plan it out so you have a slick lookin' installation

Corvettes are built to have a much do dads as possible, so the space to put them is limited. Generally speaking, stay with the speakers that will fit where the old ones came out from. There are a lot of better speakers than what you got stock. In my old 69 Vette, the car was so loud it didn't matter if you had speakers or not, you just could not hear them. They were under the dash on the side in front of the doors. If you can hear your radio, go for a better radio and speakers, maybe an amp to boost the sound. Good reputable auto sound stores will get you set up right but expect to shell out the bucks. Keep them the same size.