1987 740 wagon speaker size?

hey all, i admit, it's easier for me to pull the speakers and measure it myself, but i figured i would get a faster response this way. i wanted to upgrade the factory sound system for my '87 740 gle wagon. i did a quick google search, and i got some speaker adaptor links. now, are the factory speakers some strange size? i'm here in america, and the speakers are sold in inches. the two sizes that the local electronic store's web selector thingmabob came up with were 4 and 6.5 inches. does that sound right? also some info came up on in-dash speakers... how many speakers are there in the wagon? thanks, jun