Description TracTuff billet radiator cap bungs are machined in-house for use with my 3.00″ and 4.00″ billet tank lids, but also work on sheet aluminum projects with a 1-1/2″ hole, or being welded to the end of something like 1-1/4″ tubing. NOTE: The import cap bung has a 1/16″ NPT port for connection to an overflow and uses an early model Honda (88′-91′ Civic/ CRX and 90′-93′ Integra) cap. The domestic version has a 1/8″ NPT port for connection to an overflow and uses a late GM/ Chevy (70’s C10 Pickup w/ a 454 engine) cap.
