YOUR CHOICE DART SHP IRON SKIRTED BLOCK BORE SIZE 4.000 OR 4.125, YOUR CHOICE. IMPORTANT: UNSKIRTED NEXT IRON BLOCK THAT IS SLIGHTLY STRONGER THAN THE SHP IS AVAILABLE BUT IS A $300 ADDITIONAL CHARGE. CONTACT US TO ORDER THE UNSKIRTED BLOCK THAT REQUIRES REMOTE OIL FILTER AND OIL PAN ADATAPTER, THAT IS, IF YOU DESIRE THE UNSKIRTED BLOCK. ALUMINUM VERSIONS OF THESE BLOCK ALSO AVAILABLE FOR AROUND A $3500 ADDITIONAL CHARGE. THESE BLOCKS CAN BE ORDERED WITH 7/16 OR 1/2 HEAD STUDS--1/2 HEADS STUDS SUBJECT TO A SLIGHT UPCHARGE. OTHER MODS SUCH AS TALL DECK, RAISED CAM, LARGER MAIN BEARING HOUSING BORE ETC ARE ALSO AVAILABLE SUBJECT TO AN UPCHARGE. CONTACT US FOR MORE INFORMATION! CONTACT US FOR INFORMATION ABOUT COMPATIBILITY AND FITMENT OF YOUR VEHICLE PERTAINING TO THESE BLOCKS.