Im converting my powerglide to a muncie m-21. My powerglide's flexplate has 153 teeth. So i need a 153 tooth flywheel. But what size flywheel will work with the bellhousing, also what size clutch should i get, does the flywheel have to be externally balanced or internally? The engine is a 327 and the muncie is out of a 66 corvette.

Thanks

do you have a big bellhousing? both big 168-tooth & 153-tooth flywheels will fit in this. if you have the small bellhousing then only a small 153-tooth flywheel will fit. stock small block & big block internal balance flywheels will work provided you have room in your bellhousing. 10.5" clutch for the small flywheel & 10.5" & 11.0" clutches fit on the big flywheels. bigger will handle more power better.....

Either the larger (168 tooth) or smaller (153 tooth) flywheel with correct bellhousing will bolt up to your engine. Do not feel that you need to stay with the 153 tooth size just because that is the size of the flexplate which came with your PG. I did a PG to manual swap with my '65 and went with the larger size clutch set up. If you do not already have a bellhousing, I recommend an OEM GM 621 bellhousing and an 11" clutch set up, with 168 tooth flywheel. You will need to change the starter to an iron nose unit if you go with the larger flywheel.