Whats the difference between a BH Tracker IV and the older style Radio Shack Discovery 1000? If you look at the machines they look exactly the same. Same analog meter,knobs buttons and switches are the same as well. The only thing I can see a difference in is the search head. I know the BH is more modern,but arent these 2 just basically the same machines,with one just being older?Take a look for yourself: The BH Tracker IV: http://www.joanallen.co.uk/reports/Tk4-2.gif The Radio Shack Discovery 1000 http://arizonagoldprospectors.com/bsfree/imgs/radio shack discovery 1000.jpg See what im talking about? They are Identical,just different names. Any thoughts?