is probably dated Feb. 1988.
The 6000 Di Pro came out in mid-April of '85 and had the meter on the control housing under the hand-grip. The 6000 Di Series 3, with manual GB, was dropped, but quickly brought back to life as the 5900 Di for those of us who preferred manual GB to the automated GB circuitry.
Your version was the last in the big blue housing, if I remember correctly, and about '89 they went to the 6000 Di Pro SL. The 'SL' used a very slightly slimmer design and was in black (rod and housing) and was more comfortable to handle than the blue box types, especially with the display affixed to the end-of-the-handle. They worked similar, but they added another control to the 5900 & 6000 Di Pro SL versions called Signal Balance. That function (called Pre-Amp Gain on the XLT's that came later or Rx Gain on the current VX3 and V3i models) Let the operator increase the received gain prior to the amplification, and the results are enhanced sensitivity, stronger audio response, and you can use a much slower sweep speed with a higher setting than you can with your unit.
The circuitry was improved along the way to the final 'CB' versions, then the 6000 Di Pro SL was discontinued. Why? Mainly because it was bigger and heavier. The XLT had come out and used the lighter-weight smaller housing and was powered by 8-AA batteries in a slide-in tray. They then changed the boxier Coinmaster Classic models into the same XLT 'SL' (Slim-Line) housing calling them just the Classic series. The 6000 Di Pro SL circuitry couldn't be fitted into that smaller housing so they engineered a new model using the basic controls and excellent needle-meter display. It was called the 6000 Pro XL.
Of them all, the 6000 Pro XL was my favorite White's with excellent field performance and was much more comfortable to handle. About 2000/2001 they made a change in their model line-up and called them the 'Pro' series. The Classic IDX became the IDX Pro, the Quantum GT was renamed the QXT Pro, and the 6000 Pro XL was renamed with the '6000' dropped from the outside control housing name and it was called the XL Pro. The 6000 Pro XL and XL Pro are the same detector, just a name change.
As for your 6000 Di Pro Plus, if it is working well and you can use it comfortably, just enjoy it. They worked just fine! They are limited to the older-design search coils and do not use the Blue Max series coils which were introduced with close to the black-housed models of the 6000 Di Pro SL that came later. If you are looking for a more modern model that is lighter and easier to handle, join the ranks of us who are in search of a clean 6000 Pro Xl or XL Pro. The latter is what I am seeking (and never should have parted with he last few that I had.
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Monte
