I can tell you that on a 1990 190E the steering wheel air bag comes right out with a small torx driver [I do not remember the size] disconnect the battery first however. There is a small connector attaching the airbag to the hub. the steering wheel is held on with a large torx fasterner[ I do not remember the size] Once the fastener is loose the steering wheel pulls right off the splined hub.use a small punch or sharpie pin to mark the steering wheel and steering column shaft so the you can put the wheel back on straight. The hardest part of the job for my car was the steering wheel bolt, it was on way, way tight. use a little bit of heat on it to soften the loctite.