Just received a used savage xl and noticed right away that the 4 wheel drive was not working to the fullest like I imagined it should. Now taking it out today I noticed while doing donuts that only the rear tires are doing the power. I put it up on the blocks with it shut off and spun the tires by hand, not all four spin at the same time. The rear ones sound good while pinning while the front have a crackly noise to them while spinning. Any help to getting this thing fixed?

most likely either the front diff is ground up, or the front drive cup has lost a screw.

It does sound like something is up in the front diff or in the driveline up to the front diff.

Though you will most likely be able to get a quicker answer or a better answer over in the monster truck section as the nitro off road section tends to be more focused on the race style vehicles.

http://www.rctech.net/forum/monster-trucks-46/