I have an 03 gx470 and the suspension just gave out. The air compressor doesn't air up the rear air bags anymore. I order 5100's already and have rear springs out of a 04 4runner, do I need metal techs rear conversion kit or can I get away with just what I have? The reason I'm asking is because I'm suppose to head out on a week long off roading with my gx this weekend but now I'm concerned metal techs conversion kit won't make it here by the end of the week. Thanks so much for any help!