The model with the adjustable jaws is the most useful. If you bought cheap CHINESEIUM model, make sure you wrap with shop rag and wear safety glasses while using. Lube thread well, apply pressure gradualy and give a few love taps and it should loosen. 1956 was a long tome ago, even for me.
Sometimes you can borrow or rent from a box-store.
I never liked to use BFH or pickle forks. Too easy to cause $$$ damage.
____________________________