Traditionally workhead and wheelhead spindles were made with plain white metal bearings, this technology is 'ancient history'. The currently available angular contact bearings, give the same running accuracy as the original design, but with a much greater degree of certainty, also conferring other advantages:
Much longer life, hence reduction in servicing requirement. Also totally avoiding the problems that extreme temperature changes, have with white metal bearings.
The designs are also very ingenious, and relocate the position of the bearings longitudinally. This means that the main front support bearings on workhead spindles are brought forward reducing the distance to the chuck by 33%, this has a double benefit: both increasing the support of the chuck, and increasing the distance between front and back bearings, improving the aspect ratio, and strength. This is achieved whist leaving the live bearing position unaltered.