I make the wide body shackle spacers out of 1-3/4" round steel rod, they are available separately:
http://www.4crawler.com/4x4/ForSale/Shackles.shtml#OrderingInfo

You can also stack up two slabs of 3/8" steel on each side and grind off about 0.050" off the face to make your own (overall thickness is 0.700").