I just bought the whole axle. Someone on the team shelby site verified that it has the proper bearings. Ended up being about $1080 with shipping. Got mine from summit racing.
Oh, and yes, they whine, but I have the Griggs torque arm which kinda limits your options for angling the pinion. Don't care though. 3.73's are magic and with the Griggs kit I can keep the wheels on the ground.