Yeh, I'm afraid the "stealership" is the only place, altho' I think the bearings R available in chain AP stores. U might check there 1st before the dealer.
BTW, Dal Slabaugh @ lockitup@bright.net, or 877-448-5451 can get U at least 20-25 % off GM stuff w no tax.
My Front Diff is together, but...