Are you sure about that? What width were you looking at? As far as I know Northern Tool only carries up to a 3/8 in shackle. While the inside width is 1-1/4 in the inside mouth width is only 9/16 in.
If you are looking good shackles I am a distributor for Crosby and can get 1 in shackles for a good price. Specs for it are below. I like the screw pin type because they are very easy to install and use. Crosby makes good shackles too and these are galvanized and made in America.
A Crosby 1" screw pin type shackle should run $34.50 a piece plus actual UPS shipping.
I can also get Columbus MC Shackles for a good amount cheaper but they are import. Still really good shackles just not American made. They would run $24.76 plus shipping.
A lot of people on here are close to one of our locations so ask and I can let you know if you are and if they have any in stock.