The Th350 came with USS threads for the linkage, kick down cable, trans mount and speedo hold down in the early years, then changed to Metric in all the same holes, so it is going to depend which year it was made. Get a new shift shaft, nut and seal and swap it out, its easy and the only correct way to fix it, and while you have the pan off might as well change the filter. Hope that helps!
The Jalopy Journal
