GM-GMC: 4 wheel drive on 2000 gmc, gmc 1500, rear wheels

Question
i have a 2000 gmc 1500 pickup.  the frt and rearend are out of a 1999 model.  the truck runs fine in 2 wheel drive but when i engage the 4 wheel drive it makes a roaring noise and if the steering wheel is cut in any direction the rear wheels seem like they are trying to push the frt wheels.  the gear ratio is not the same as was in original truck.  does the transfer case have to match the ratio of present frt and rear?  also need a wiring diagram for the 4 wheel system.  where is the best place to obtain?

Answer
It sounds like something is binding for sure.  Hopefully you are not doing this on pavement, also make sure you have matching tires with similar tread depth on all four corners.  A difference in tread height can cause a system to bind up.  It takes very little difference in tire height to have one tire turning faster or slower than the rest.  I need to know a little bit more to be accurate.  First is it manual shift(floor shifter) or electronic(push button) 4x4?  What section do you need the diagram for? The transfer case, the front diff, the shifter???  I would also require somewhere to email it to.  I have no way of inserting or posting a diagram on this site.  
Thanks