Yes, the TNT non-inverted Mk5 bearing is a significant upgrade over the previous generations. The older TNT bearings were made out of aluminum and were attached using 3 small bolts. The Mk5 bearing is made out of stainless steel with MUCH greater mass. The bearing is mechanically coupled to the plinth using a very fine threaded 3 inch stainless steel collar which secures the bearing much better than the previous versions. In addition, the Mk5 bearing has much thicker Rulon (sp?) bearing collar sleeves which are made to a higher tolerance.
Some Mk5 bearings do not come with the 3 inch threaded mounting collar but come with a traditional nut and bolt combination, although not as attractive, performance wise they are the same. I own three examples of the TNT bearing. TNT Mk3.5, TNT Mk5 with nut and bolt, and a Mk5 with the 3 inch collar. The end result with the Mk5 bearing is a quieter bearing with improved micro detail and dynamics
VPI no longer stocks the MK5 bearing, therefore finding a bearing will be your challenge. The Mk5 bearing is a drop in replacement for older TNT bearing. The TNT Mk5 inverted, Mk6 and HRX inverted bearing require a larger bearing hole, therefore, older TNT tables will require modification. I am not sure if the new inverted Classic bearing will fit a TNT. Hope this helps