8.8 swap

So the insides of these axle tubes have a semidry sticky black gunk in them. I am assuming old clutch friction material mixed with old gear oil. I need to pull the ring and pinion out and clean out the gear oil and this black sticky **** out of at least on one side before i finally weld this thing up. How have you guys douched out these axle tubes on your 8.8 i was thinking laquer thinner and a 1" or 2" paintbrush attached to a long stick and that would prob work fine on the left side with the end cut off, but the passenger side notsomuch.