Brand new Crower Enduro Centerline Roller rockers for BBC. 1.7 ratio. 73687-8 .090" backset trunion, and 73683-8 .050" backset trunion. These were mocked up, installed and the engine ran at idle for 10 minutes total. Did not work for my application. Backset is for when using longer than stock valves. New these are $800 from Crower, will sacrifice for $500. Shipping included.