Gears & Axles - From 4 channel to 3 channel

I recently replaced my 4 channel rear end with a 3 channel rear end. The ABS INOP light is illuminated so is TCS. I want to fix but i dont know where to start. Has anyone done this? And about how much money do you think it will be if i do it all myself?

Many have done this,common problem/mistake.
If you still have your 4 channel rearend,it'll cost you nothing but time. You have to use the 4 channel axles and backing plates/dust shields into the 3 channel rearend. Both have to be taken apart to the point where the c-clips can be removed and parts swapped.
4 & 3 channels are not interchangeable,different electronics and brake hydraulics.

thanks i appreciate it. :cheers: