The long heat shield in the middle of the car; the one between the exhaust pipe and the floorpan; it attaches to the floorpan - has come loose on my car. One of the long hex nuts that stands the shield off from the floor is missing and I can see what looks like a threaded stud sticking down. Does someone have a good diagram of this connection? Or can explain exactly what it is? Is the stud welded right into the floorpan, or is it a replaceable fastener? I haven't had a chance to crawl underneath yet. What thread size are these parts? Thanks. My Haynes manual doesn't appear to have the correct diagram for a 97.

The hex nut to which you refer is screwed into the floorpan. You probably just lost the 10mm bolt that goes into it. Not sure of the pitch , but it is a very common bolt used on tese cars. The same as one of the bolts holding the fender on.

 

Hopw that helps.

Don't be surprised that the Haynes manual is erroneous. I have found that these manuals are notoriously error filled. They also seem to forget to include important information way too often.

 

Obviously, no aftermarket manual will be the same as a factory shop manual, but these are the worst, in my opinion.

should be m6x1.0 thread. take out one of your fender bolts and bring that with you to the hardware store, that will be the correct thread to find a nut for.

the hex piece is essentially a long nut with a stud in the end, to space down the pan for Outback models.

Turns out, they are M8.

 

The 4 long hex fasteners are all the same. They are similar to a coupling nut, but with a threaded male stud sticking out one end and a blind female hole in the other. The 2 in the middle have the male end screwing up into the floor pan. The 2 on the back end have the female end screwing up onto a stud sticking down from the floor pan. :-\ Subaru, what the heck?!

 

Anyway, they all came loose without much trouble. I used some large flat washers to hold the heat shield in place. The one rear stud was ripped off, so I didn't do anything about it. With 5 of the 6 total fasteners back to a solid condition, the shield is no longer rattling and I'm not worried about losing it.