I need to replace the wiper fluid pump on my '69 Executive. The stock one has never worked since I bought the car (~7 years ago), but it would be nice to have. There is still wiper fluid in the resevoir, which is probably 30 years old!

For any of you classic guys that know about these kinds of electronics, can I use ANY pump that will fit in the same spot? Or do I need a specific GM replacement part? I thought I'd ask here before searching for parts from Ames or Hemmings. Any info is much appreciated.