This is just a note to add to the"Wish I Knew" list. I have a leaky brake master cylinder that I have started to replace. There are 2 bolts on the inside of the front fire wall that hold the Master cylinder into the vehicle. What I didn't know was that there are two ferules or sleeves on those bolts between the two walls of the crossmember that mount the master cylinder. When I removed the bolts, the ferules fell down into the crossmember. (Rob and Dave's web site refer to that cavity as the "Black Hole"). ( I should have read their advice before I started this mess.) I put a magnet down into that well and retrieved one of the ferules, the other apparently rolled down into the tunnel and is gone forever. I made a new ferule and proceeded to mount the master cylinder. This is normally a two man job. One holds the cylinder up on the frt. side and the other puts the bolts back in from the inside compartment. I figured out a way to do it alone. I put a 4 inch 1/8th dia. bolt in from the frt. and pushed through the firewall and put a washer and nut on inside and put a wrench or vice grip on nut and go back under and tighten it up until cylinder is almost in place. Then could put a bolt in from the inside and secure. Remove the 1/8th bolt and replace second bolt. Not easy but works. The bottom line here is DO NOT pull the bolts out of the firewall when replacing master cylinder, just unscrew and then pull cylinder forward off the bolts. If the bolts must be removed, the ferules will come out through the same hole as the bolts, but you need to be sure they are coming out along with the bolts as they slide back. You can get your fingers inside the crossmember and work the ferules rearward to assist the removal. If they fall off inside the member, it will make you cuss.