if your rust bubbles are like my rust bubbles on my 89 xj(resembeling boiling water) when you sand them they will be holes.just use a dremel if you have one or can get ahold of one and grind from inside te hole out till you get to "healthy" metal.

out of all the jeeps in this town the d**n gremlin had to invade mine

I've done so much,with so little for so long i can practicly do anything with nothing