Darton can make them to your specifications.The thin wall style they have are around .060" thick, and are replacement sleeves more specific to aluminum race blocks like Rodeck and Donovan that have an additional 1/4" or more of material surrounding the sleeve to support it. These blocks can be as thin as an 1/8" or less. You'll remove half of that thickness to bore out to install a sleeve. Unless you have a Mexican block that is much thicker, you'll not end up with a better block by sleeving one. Leo's comments are mostly race oriented on this matter and for blocks that will be filled. So not too relevant for non-race applications, unless again, its regarding a Mexican block. We wouldn't even consider a non-Mexican block to start with because our cutoff for wall thickness was .125", and most of them were below that at .060" or less on the major thrust side.
