Normal behavior of ABS in Colorado 4 X 4

I have a 2004 Colorado 4 XS 4 with ABS. WHenever I break on snow/ice/water where the truck even begins to slide a little bit the
brake pedal pulses violently and there's terrible metal-on-metal grinding sound from underneath the truck.
I understand why the pedal is pulsing, but is it normal for there to be the grinding noise? I've had other vehicles with ABS and I've never heard anything like it.
The truck also has a rear locker, in chase that's useful information.
Any input appreciated.
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