I lucked into some grade 8, 3/8" all-thread somehow. It won't strip out like the soft steel which most all-thread seems to be made of. I use the 1" long coupler nuts to spread the work around along all of the additional threads compared to a standard 3/8 nuts. If I have a bushing that is extra stubborn, I use a propane torch to warm up the spring end or the frame mounted bushing bracket a bit to create a little expansion.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission