[size=medium]The 'original' 6000/Di PROfessional came out of production mid-week in mid-April 1985. It had some very good concepts, but still a few 'bugs'. It was housed in the old familiar blue housing with the handgrip on top, and the TID pod mounted on the front of the handle like the Series 3. One difference was the new 6000/Di Pro had the colorful meter display back. What made it a "Pro"fessional was the change from manual GB to the auto-tracking circuitry.
While there were some revisions along the way, the physical package remain unchanged until 1988 when they changed the name to 6000/Di Pro Plus. The easily seen differences were the new contoured rubber grip, the new paint, stainless steel hardware, precision-fitted rods, the new Hot Rock Accept/reject circuitry and ... easiest to see of all ... the new Blue Max 950 coil was standard.
In very late '89 or early '90, White's went from the blue metal housing with silver rods, to the black housing that was under-slung below an upper forearm rod with a stand-up grip (the TID display mounted on top of the grip), and an 'S' middle rod and lower rod, also all black. This made the balance and 'feel' of the 6000/Di Pro SL ("Slim Line") far superior to the former physical design. In addition, the main added feature was Signal Balance. The 6000/Di Pro SL and all other 6000/Di Pro offerings to that point were powered by the drop-in 4-C cell battery pack or equivalent rechargeables.
The 6000/Di Pro SL went through a few final revisions of the rod design, as well as circuitry enhancements.
In 1994 the XKLT was introduced in the smaller housing and powered by a drop-in tray of 8-AA batteries. Smaller and lighter weight, it appealed to many.
In mid-to-late 1996 White's introduced the Classic series in this smaller housing as well as the Quantum series. In 1998 we saw the Classic ID introduced in this small housing, but the 5900/Di Pro and 6000/Di Pro were still the bigger, heavier, chunkier models in their line-up.
Somewhere about '99 we saw the introduction of a brand new model to replace the famed 6000/Di pro. It was called the 6000 Pro XL and was housing in the newer, smaller housing with 8-AA batteries powering it up. It was NOT the old model crammed into a new case. It was a completely engineered model designed to come close to the great performance we had come to know, with that excellent analog TID. In about 2001 they made some model name changes to add the "Pro" series, again, and the Quantum XT became the QXT pro, the Classic IDX became the IDX Pro, and the 6000 Pro XL was renamed, simply, the XL Pro. Same unit, different name.
I hope that helps.
Monte[/size]
