Might note that 91 was a transition year between the earlier "C" 3800s which have a "slip fit" balancer and the "L" 3800 which is a press fit. It it needs to be replaced, make sure you get the right one.

Haven't experienced a balancer failure but have been told that it sounds like a rod bearing knock that goes away when you remove the serpentine belt and with the engine off, can feel movement in the rim.

Just thought I'd give you guys an update....

Aftermarket balancer was installed.. cost me $270 for the part, and almost nothing for the labor.

Had the transmission completely rebuilt for $1250.
She'* running pretty good now, there'* a new rattle somewhere (I think exhaust)... but I haven't been able to track it down yet.

It'* very suttle... I can only hear in INSIDE the car... when the stereo is off.
It'* coming from the rear, but I can't hear it outside.

Anyways... just thought I'd let you all know how I made out.