The shackles just bolt to the frame and cab with 3/8' coarse thread. I think 1 1/4" long will do. I used locking nuts to ensure they don't come loose. The front cab mount bolt I used grade 8 1/2" I believe. Can't recall how long it is.
The rear shackles bolt through the cab floor and thread into a little plate that has two holes tapped. If you've lost it, it is a simple piece to build with a piece of steel, drill, tap and grinder. Brad's picture shows these plates on the left hand side.
