GMC Repair: transfer case 2002 safari van awd, planetary gears, safari van

Question
when i turn the wheel the van seems to jump or jerk (sort of a pulsing) i was told it could be in the transfer case or could this be the planetary gears in the rear differential?

Answer
it could be something in the transfer case, or depending on the mileage and what kind of maintenance as been done you may just need to flush the transfer case fluid.  Also check to make sure that the tires are all the correct size and properly inflated, if you have one tire that is worn more than the rest, it changes the height, and it will cause numerous AWD issues