I had a set of those Fatman Fab ones on my dart. They are based off the F/J/M/ late B body spindles. All it was, was some steel stock to make the backing, a lillte square stock to extend the ball joint hole out some and some round stock reamed to the specified size and depth for the ball joint on the top.

Pretty easy and basic if you ask me. I want to say it was 1/2 steel for the main part. The spindle itself was machined and looked to be a press fit into the backing---it was definatly not a 1-piece deal like the factory or chassis tech dropped dakota spindles are.