If your car came with U63 (AM mono radio) or U69 (AM/FM mono radio), it would have come with a single front speaker in the dash. However, you could also order U80 (single rear speaker) if you wanted.
If your car came with U57 (8 Track stereo tape player) or U79 (AM/FM Stereo radio), then it would have automatically come with two front and two rear speakers.
Ed