So I took down the cross member and tranny mount on a 97 legacy to change the shift linkage bushings. As if that job wasn't a pain in the rump roast already, I ran into some trouble putting it all back together. When I was putting the cross member back up (the one in the front of the tranny held up by 2 17mm bolts) I tightened the left one without a problem and when I was tightening the right one I must have cross threaded it. The 17mm bolt goes through the cross member, through a hole in the frame and then threads into a nut welded on the inside of the frame. Since the bolt was cross threaded I over torqued it and snapped the weld off the nut on the inside of the frame. The bolt and nut now both spin loosely and the cross member bangs around when I drive. I can't get to the nut because its on the inside of the frame and there is no opening to access it. If anyone understands what the hell I just said please let me know how to fix it. Thanks.

Hmm, sounds like you need to cut out part of the chassis to access the bolt, then you can put on a new nut and weld it into place and then oil spay inside the area and weld back on the piece you cut out.

Lift the carpet and cut a hole in the floor with a hole saw to get at the welded nut.

You'll have to cut a hole to get access to the nut. That's about all there is to it. Whether you go in from the side or from the top is up to you, but either way will be fine.