Sometimes you can clean out the pump and get a bit more life out of them. This is from the how-to

1. Drain your heat exchanger by opening the pet**** valve...or clamp off the lines going into and out of the pump
2. Take off the two hoses that connect to the IC pump
>>>IC pump is located on underside of front bumper (towards driver side)
3. Remove the pump from bracket (2 8mm bolts on top of pump in center)
4. Remove the six screws from front of pump once off the truck
5. Take apart the front side of pump and you'll see all the build up of black cake like crap
6. Lightly tap to break it loose and dump it out
7. Replace the pump back together (make sure both orange O-rings go back)
8. Reinstall pump and lines, refill with drained or new coolant/water wetter mix

If that doesn't work, here's one place you can get a new one: https://lmr.com/item/M8501LSVT/1999-...mp-M-8501-Msvt