Something I have found works in some cases is measure the depth of the hole. Then subtract the length of the bolt. Hopefully you will find the hole has room for a longer bolt.
Lets say that you find the hole is 3 1/2 inches deep and the bolt is 3 inches then go to the hardware store and get a bolt 3 1/2 inches long with the same threads. If it won't go quite all the way in you can use a washer or 2. The threads in the very bottom of the hole have never been used and usually are strong enought to get the job done.

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84 500 SEL (307,xxx miles)