Essentially, the ProLab D6 was a deluxe version of the D2, although, once again, there were differences in the chassis construction. It was an XL chassis equipped with a three-lens turret, micro focus attachment, masking attachment, and the triple condenser Zoom lamphouse, which had an external knob to adjust the third condenser, eliminating the need for separate condenser sets, or manually moving the third condenser as with the DV lamphouse. The D6 also came equipped with an extended bellows, eliminating the need for a variety of lens cones for different focal length lenses. With so many convenience features, it was very much the "Cadillac" of enlargers.
When the D2 was discontinued in the mid 1970's, the D6 chassis went with it, along with the zoom condenser lamphouse. But the D6 immediately resurfaced as the Super D6 ProLab enlarger, now based on the D5XL. However, in this case, there was no difference at all in the chassis. The Super D6 was simply a D5XL that came with the turret, masking and micro focus attachments that were optional for the D5. Therefore, for the listings for the Super D6, please refer to the D5 page.