I wrote Hubcity about the issue for my B6000 and Gary King wrote this back to me maybe it will be helpful for you. Oh and check around every once in a while people have the reverse for sell, I'm looking if I find two I'll let you know.
It is true that we have "in the past" produced a gearbox that was designed to reverse the Kubota B6000 tractor rotation, it was old part number 0220-01402. We do not presently make that gearbox. We can however make something similar. If we modify a current Model 22, 1/1 ratio, style SO, to have a 31/32" 10 Splined hollow bore and a 1-3/8" 6 Spline output shaft we will achieve the same effect of reversing the rotation and converting to standard PTO size and spline. The old gearbox was actually a variation of the current model 22. The main difference is that we no longer can make the Mounting adapter that was on the 0220-01402. It would be necessary for you to find a way to mount it to your tractor.
Since we do not do direct sales, please note the following are distributors in your area that you can work with.
EASTERN BEARINGS INC
7096 S WILLOW ST
MANCHESTER, NH 03103
Phone: (603)668-3300 Fax: (603)669-5714
KAMAN INDUSTRIAL TECH #125
3 PERIMETER ROAD
MANCHESTER, NH 03103
Phone: (603)669-6105 Fax: (603)644-0195
APPLIED INDUSTRIAL TECH
649 E INDUSTRIAL PARK DRIVE
MANCHESTER, NH 03109
Phone: (603)623-8897 Fax: (603)623-8763
MOTION INDUSTRIES INC
444 EAST IND PARK DR - UNIT 10
MANCHESTER, NH 03109
Phone: (603)641-5649 Fax: (603)641-5738
Thank you
Gary King
Hope this can help, Jerry B6000 owner also.....