How do you remove the differintial on a 2004 chevy pick up 1500?

Get the rear wheels off of the ground, remove wheels, and drums. (Rotors if you have those)
Remove rear cover (use a drain pan to catch fluid)
Look for the 5/16" or 8mm head pin bolt and remove it.
Turn the differential so you can get the pin out. (goes through the center)
Push you axles inward and with a small magnet, take both "C" clips out from the inner part of the axles.
Now slide out you axles. (Careful on the outer seals)
Mark your carrier bearing caps so you know what is left or right, and remove them both.
Find out what size the bolt heads are for the "ring" gear and get two wrenches to fit. (Usually 19mm or 3/4")
Hold one on a bolt head on the top side and put the other wrench lower.Force the lower wrench upward, as this will push the upper wrench into the housing and "push" the differential out. When removing be aware that there are spacers that need to go back where they came from. DO NOT MIX THESE UP. These spacers are under the carrier bearing caps, left and right of the differential.
Note, four spider gears is a normal differential, requires gear oil. If it has clutch packs, it is a limited slip and requires gear oil and limited slip additive!!!