Upgrade yor 3100 or 3400 engine with this 3500 "top swap" conversion. This kit comes with everything you need for the job including the 3500 cylinder heads (with options for our Stage 1 and Stage 2 portwork and valvetrain), ported 3500 lower intake, ported 3400 upper intake (or newer 3100 large port upper intake), and all the AC Delco gaskets and parts you need for the job.