Just installed a auto with 4000 stall was previously a manual as of 300 miles ago. The auto is a new FLT, I have the stock rear end with 4.10 gears that have been in there for atleast 30,000 miles no problems, i have drag radials for atleast two years now making 525 hp flywheel. As of today i notice a loud whine coming from the rear almost like a tornado siren it starts at around 30 mph this has never been a problem before untill today when it started.
Any ideas of what to check first, Thanks.

 

still stock 10 bolt ? 10 bolt with drag radials= die, you luck it last 2 year. sound like you need looking for new rear end, 9 or 12 will be fine, btw drop the rear diff cover and check to metal peice, change the fluid too.