That TT part#1165 (factory#2921) Front Bearing and Spring Clip isn't very rare, and they are found many times on put-together car chassis, as commonly are unknown by many of the presence of two different spring clips, (car part#3075B), the smaller of the two.
Best look would be to cut the threads shorter, re-drill for cotter pin hole, and use castle nut, with the bigger thread on the TT front bearing, you can use rear axle shaft nuts, they are the same thread size.