We use and sell both blocks,the two are the strongest out there.the Brodix is finished a little nicer but needs align honing after you get it.the Dart has a universal lifter area that is solid so they can put the lifter bores anywhere.that adds a small amount of weight.the Brodix is set up for 50mm roller bearings and the Dart is set up for B.B. size bearings.I think when it comes down to which one to buy Its who ever has one in stock.Bill