A question I get asked a lot is,"Will a 3/4" Shackle Pin fit inside of a Crush Proof Thimble". The answer is not simple, but is most likely what you want to hear. To start, the minimum inner diameter of the cruch proof thimble is 7/8" of an inch. On some 3/4" shackle, it's easier to fit the body of a shackle into a rope thimble than the pin. This is what we prefer for real world use. You can't usually fit a shackle body through a bumper shackle mount, but you can fit a pin. If you are using a snatch block, the is what would most likely be required.

On some 3/4" shackles where the pin will fit, but the body will not.

Below you see two 3/4" shackles. The one on the right is a 4.75 ton shackle. The one on the right is a 7 ton shackle. The pin for the 7 ton shackle will not fit in a Crush Proof Thimble, however the body does.