What gear oil do you guys use in your Dana 30/Dana 35? Conventional or synthetic? From what I'm reading it's just over 1 quart for the Dana 30 and 2 quarts for the Dana 35. 80/90 is the suggested weight. I'm changing the gear fluids on a 1996 Jeep Grand Cherokee Laredo. Did any of them come with a trac-lok? Just wondering if I needed to pick up some additive for it. Thanks!