My 2001 Suburban 4x4 requires the Gm autotrak II fluid. Is there a synthetic alternative I can purchase at Autozone or Pepboys or do I have to go to the dealer? Also where is the transfer case? I've changed the motor oil so I found that drain plug. I located the tranny pan and plug which is on the passenger side further back from the oil plug. Just not the transfer case. Does anyone have a diagram or anything?