yep .. I missed the question last night .. Thanks kevin .. A very handy tool for locating vibration from a car or truck .. It will find front wheel hub bearing noise before the human can feel it or hear it ..i have one myself for my car collection .. I got tierd of loaning it to the shop so i bought the shop one of its own .. It was stolen three days later .. They only took the best of the best and left the second class stuff in its place .. They knew the shop tools thats for sure .. I had three locked work benches they only broke into the one holding all the electronic test equipment ..if the same type i've used back in my dealership days, it's somewhat like an electronic tuning fork, it can isolate which frequency is causing the vibration.
Wheels/axles have a different peak than say a driveshaft and engine speed can be varied to differentiate the driveline. Very interesting tool.
We used to see a lot of complaints of vibration on acceleration with certain chassis combinations, especially suburbans and trucks using the 2-piece driveshaft with center bearing mounts.