hey guys, I have a 66 Impala with the original aluminum case powerglide... car came stock with a 327 but has been upgraded to a 350 (prior to my purchase)... recently, i have been noticing a grinding sound when I get on the gas a little harder than normal (not mashing it, just moderate acceleration)... the noise occurs primarily in low gear, but I have heard it in high gear as well... any ideas what problems specifically I might have in the tranny? Is it a clutch/friction plate problem, or maybe the planetary? I have a better than average working knowledge of most things automotive, but have tended to leave automatic trannys to the pros in the past. everyone tells me this is the easiest auto trans to work on, but I would like to at least have a good idea of what to look for when i begin the overhaul.. i wouldn't want to miss something and negate all of my work... thanks for the help!

 

sound's like the planetary or sprag bearings