buzzing from rear of car

["Theodore R. Harlan" <trharlan@one.net>]

Car is an 86 5k.

I have a buzzing. Kind of a grinding, metallic buzz. Inaudible at idle,
increasing with car speed.
Replaced the fuel pump. Ever put a really deep cut in your hand while it
was submerged in gasoline?

Absolutely no change in buzzing with new (used) pump. Buzz has increased
greatly in intensity over the past 50 or so miles. The car drives fine.
The sound is almost definitely from the car's rear half.  I am virtually
certain that the sound is not a wheel bearing or suspension related.

Do not want to drive car 15 miles to mechanic in case problem is very
serious or still fuel-related.

Uhh... help?

Ted Harlan