Tektronix's original promotion for these printers offered “Free black ink” for the life of the printer. The tag line was ”Brilliant color when you need it, free black ink when you don't.”. This is done by including some black sticks in each color package. This results in 1.5x to 2x as much “free” black ink as color when you buy all three colors. If you didn't buy enough color, you could order additional cases of black for free from Tektronix. (Yes, the packages of just black solid ink sticks are usually re-sold freebies!)
Today, boxes of color ink still contain “free” black ink. But what happened to the free additional boxes of ink? Xerox still has the above box on the Phaser 360 page, but clicking the link takes you to the Phaser 850/860 free black ink page.
A quick Google image search showed the Phaser 850 blocks were a very different shape, and the phaser 850 had a different heater design, but not only were Phaser 860 blocks and Phaser 360 blocks similar shapes, people were refurbishing Phaser 360 drums with Phaser 860 heaters! I took the plunge and tried to order some 860 supplies.
The checkout process made me register and confirm my Phaser's serial number (I used the 360's), and pay $9.99 for shipping, but the confirmation page did promise supplies were on their way to me!
Through the magic of TV we'll skip ahead 3 days
Purolator delivered my Phaser 860 supplies from Xerox. Opening the outer packaging, I found a box of three Phaser 860 solid ink sticks.
Notice the prominent “Free Black Ink” on the front (and sides and bottom) of the package. These very same boxes are on eBay for up to $20/box.
The actual cartridges are a mildly different shape, having a bowed middle and shorter length. The bottom of the 860 ink is obviously stamped “Xerox 4” while the older 360 ink is stamped “Tektronix”. The actual ink has a similar hardness and feel, but the 860 ink has much “sharper” edges and a visible layering compared to the very smooth 360 ink. The 860 ink also doesn't exhibit the white-surface build-up the 360 inks due. My milligram scale shows the 860 block at 34.49 gm vs 39.48 gm for the 360 block or 12.6% lighter.
The Xerox ink does fit through the 360's ink loading gate with a slight push. For the purposes of testing, I've loaded the 860 ink as the next block to be used, but even after a week of heavy printing, it hasn't made it to the melter yet!