The problem was only with the bolt - not the shackles. It is a special bolt and your standard grade 8 bolt will not work. The shackle bolt is drilled hollow about 1/2 way through so grease can flow to the middle where there is a groove machined around the bolt to allow the grease to flow into the bushing. The end is also tapped to accommodate a grease fitting. The ones I ordered through O'Reilly Auto Parts fit perfectly and torqued without any problems at all. They are a kit and come with the bushing, nut and lock washer. The part number is TPSK108 and I believe they were manufactured by Rare Parts. Other parts suppliers like NAPA also show them on their website, but they are a special order item for them too.
