I think they are trws or sealed power-I have the in a box on a shelf in my shop-the block ended up having a crack in the bearing housing that I was going to build so I had to junk the block and scrap the project, I also have a 14 bolt baffled oil pan, new front cover and waterpump,214/224 cam with gm lifters-I could possibly sell everything as a package and also 3 new front billet caps. Matt 347-680-8642.