What size speakers do I get to fit a 1991 Nissan Patrol Ti?

Best way to measure it out so you dont make multiple trips is go to walmart in the parking lot take out one of each speaker. Its not that difficult to do just dont kill the wire. Bring them in make sure they know u brought them in and go look at the wall where they are on and stuff. Most walmarts have them. Measure it up like that because you need the holders to match up too unless you feel like making new holes fore some styles of speakers