Pete,
We are presently buying these busings from Applied Industrial Technologies......Greenville, SC. 864-288-09080. We are using the QD bushing - size SH with 1/4-20 bolts. These bushings are ordered by shaft size....they come with different bores. This of course has to be matched to the hub that you use. Also, there are other MFGs of these bushings. Browning is the other one that I know of. You can search online for "taperlock" bushings and you should get other results.
Ed