Being an 07, you might still have the paper tags stuck on the axles ... you may have to look for the info stamped into the axle tube. Amongst the info on either there will be a D58 or D60 or D70. These numbers stand for 5800# / 6000# / 7000# axles. All bearing re-packs play out about the same save the never lube axles. Jack up an axle (I won't get in to the placement of the jack) and remove the wheel and tire, Pop off the dust cover and remove the cotter key, spindle nut , and washer. Work the wheel hub a bit and remove the front bearing. Slide the entire wheel hub from the spindle. Remove the rear grease seal and the bearing. Clean both bearings in say solvent and dry, then repack by hand or with a bearing packer (well worth the money). Clean up the bearing cavity in the hub and put the rear bearing back in followed by a new seal (lip faces towards the inside). Look over your brakes and clean them as well as the backing plate. Reinstall the wheel hub, front bearing, washer, and nut. Wrist tighten the nut while spinning the hub and install the cotter key and dust cover. Put the tire back on, lower to ground, and tighten lug nuts ... go for the other 3. I left out some odds and ends, but you get the picture. Google trailer wheel bearing repack for more info.