i just bought some tail lights for a 1996 toyota corolla. the car im wantin to put them on is a 1996 geo prism, which is the twin of the corolla. im wonderin if i will run into any problems with the tail light housing units being different, even tho the cars are twins. can anyone help me out?

Yeah. The car you are trying to install the taillights on will mostlikely have "taste", and reject the tails.