Bingo Dave! The metal grease shield that rides on top of the front motor mount was touching the harmonic balancer. You can see daylight thru the metal shield where it was rubbing! The 216 that I replaced in '92 didn't have that piece and neither did the '55 235 that went back in. Trying to do everything right this time we installed it like original but I guess the '61 235 didn't like it there! Gone now and although I haven't run it yet I'm pretty sure that was the cause of my 'curious noise'. Thanks for the insight guys, this forum rocks!
