2000 Century Speedometer

My speedometer has an intermittant failure. It will read accurate speed then drop to zero, then back up to speed and back to zero. Seems most effected when leaving a stop, or while cruising and hitting a bump in the road. Some days it will read perfectly all day, other days it's off and on. No SES codes found.Transmission was just rebuilt, I'm wondering if the VSS connection is lose or working it's way lose. Where is the VSS located? Is it easy to get to/replace?

Another problem that appeared since tranny rebuild is my downstream O2 sensor intermittantly fails. I have a scan tool that shows me the O2 values as I drive. Sometimes the downstream O2 sensor works, sometimes it doesn't. I've replaced the O2 sensor with the same results.

I'm wondering if my problems are related. Do the wires from the VSS and the downstream O2 sensor run in the same wire loom? Did the tranny shop possibly damage the loom? Any thoughts?
Thanks,

For VSS location on the 4T65E autotransaxle see link below.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=760735)