It came off of my uncle's small block roadrunner in the late 70's early 80's. I think it's 108 LSA. I had a picture of the part number somewhere I believe. Wish I could recall the # from the top of my head, but I installed the cam over a decade ago. Yeah, the 40's were pretty awesome when I had them on the car (8 months ago or so). You can really hear the cam with those chambers. My friends could hear me rev matching a few street blocks away before entering the plaza. Random folks and friends thought it had a big block with the 40s on.