Ended up breaking a U joint and it broke the back of my stock case glide. I was in a time jam and went with a 1500 HP ATI super glide aftermarket case 1.80 gear set. Old trans was a basic stock case / tci input shaft, 7 clutch ATI direct drum, kevlar band, TCI brake, and 1.76 TCI helical gear set. Also went with new molley drive line and larger 135O billet yokes. Added about 8 lbs. 60' is off Mph is down a solid 1-1.5 in 1/8, and 1.5-2 in the 1/4. Similar Da and no other changes. New trans doesn't feel like it's slipping but shift is a good bit softer than old trans, and there is a lot more growl at idle. Kinda sounds like a old pete jackson gear drive. Also notice flex plate flexing forward a little when you rev car up in Park. Converter has about 1/8" of clearance. I was expecting same time or a little quicker from the straight cut planets. Could the hd parts be soaking up that much power?