I finally got around to installing a new speedo cable today after suffering with a bouncing speedometer for 3 years. I had the luxury of using Dave's (4Pipes) lift, which made life a LOT easier. The biggest PIA is removing/reinstalling the knurled nuts that hold the speedo on. It's a much easier job with a spare set of hands.
Mission accomplished. The speedo is now rock solid. It's a little off, but at least I know where I'm at and it's not bouncing back and forth in 10 mph increments.
Thanks for the tip regarding the Napa PNs guys. The Napa cable (615-1644) is perfect and we installed a new rubber O-ring at the same time (727-2115). The existing gear and clip was in perfect condition so we reused that.