Quote Originally Posted by NTFDAY View Post
After I got out of the Corps in 66 my cousin moved to Ca. and stayed with me for awhile. Somewhere he acquired a Hillman though I don't remember the year. It was a bear to work on as nothing fit. I later found out most everything on the car was British Standard or Wadsworth or a combination thereof. I used an Arkansas speed wrench on everything I could.
American threads and English (Imperial) threads differ, and Imperial thread and head sizes differ amongst themselves too, for example a spanner for a 1/2" British Standard = 7/16" Whitworth.
The only threads that are compatible are UNF and SAE, although they too differ (if my fading memory serves me correctly,) in 9/16". (Or is it 7/16"? I forget. It's one or the other.)

...and I too am curious as to what an Arkansas speed wrench is...