Hi All
The 99 up Galant (and others) fuel pump assembly is held in with a large plastic nut. Well, I found that the thing comes off easy enough, but it doesn't like to go back on quite so easily. Since the nut and tank are both plastic, it seemed that the nut thread didn't want to start very well.
So, I heated it up with an electric heat gun...not too hot, but enough to make it grow. That did the trick.
Pic of nut here:
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Gerard