Our new billet steel main caps finally allow you to upgrade the strength of your block for an incredibly reasonable cost! With the increased popularity of our stoker kits and forged rotating components, the block and factory cast iron main caps are often finding themselves as the weakest link in modern stroker engines making over 600-650 horsepower. With these upgraded caps, you can extend the reliability of your factory block far beyond that range... and for a small fraction of the cost of other main caps on the market, or especially an aftermarket block. These caps are FACTORY HEIGHT. That means they are compatible with any off-the-shelf Big Block Mopar main studs or bolts (no special lengths required) and they'll work with any of the aftermarket girdles available (for a super strong combination) AND you won't have interference issues with the aluminum rear seal cap due to these caps being taller than stock. The bolt holes are spot faced to make sure the main stud nuts and washers have a flat, even surface to clamp down onto, and the thrust surface is already pre-cut into the #3 cap. We've thought of everything. And, the best part? We include ALL FIVE caps for the incredible price listed. A great choice for upgrading an old set of cast iron factory caps, or even for replacing a set of missing originals. These work with both "B" and "RB" engines. As with any aftermarket main caps, fitting the caps to your block's registers and line boring and/or honing is required.