reply>I use that socket and about 3 other combinations of tools to install and remove the plugs, still going to drill holes for # 5 some day. mine has raised port heads, they are longer, wider, and taller than most other heads. Have about a 1/2" clearance on the firewall at the back of the heads= no heatermotor there. headers are 2"tti, very tite squeeze everywhere on both sides. firewall floor seam flattened and welded solid, no room for trans blanket or shield.-- 68 fastback form S, motor plate, and aftermarket front end. Everything clears, but barely.