I'm assuming it's a wheel bearing that your talking about not a pinion bearing. If so then no, you don't have to get into the dif. You need to take the brake drum and brakes off and behind the axle flange there are 4 nuts that you have to remove. Pry the plate off that the nuts held on and you should be able to pull the axle out. If the axle still doesn't come out even with some prying, then find a socket or something to fit over the nut on the end of the axle so you won't damage the threads ( I'm assuming that it still has the 2 piece axles) And hit it hard with a big hammer. It should pop right out. If it doesn't, Hit it again.