eBay 4 million reasons you'll find it here
 
    These are ground straps, past & present.  Our alternator went belly-up after just 2 years! While attempting to diagnose the problem we found that the voltage, while stable back at the engine, jumped all spikey-like at the front of the car. It turned out to be the little mongrel of a dirty and corroded ground strap shown in the top of this picture.  Replacing it with the shiny new stainless model did the trick.
Expensive lesson...
 
    The strap in question runs between bolts on the transmission and the frame, at the front transmission mount.  Here, Tracy cleans the frame-side of this mount with a stainless wire brush to ensure good contact.
 
    Tracy tightens the mounting nut on the tranny side to finish the job.  The stainless ground strap, while somewhat pricey, was certainly cheaper than an alternator...