Don't do it. The pucks will fail on you.

No one uses them on 4x4's anymore because they can't take the abuse.

Use poly bushings from companies like Daystar, Prothane, MORE or original rubber bushings but not pucks.

It just ain't right.

PS: If you own a 63-72 pickup then check this out:
http://www.tellico4x4.com/index.php/cPath/419_3007?osCsid=a94c2787259caf3006abc17247315c9e