For about the same price you can order an axle from Ford with 3.73s (KR axle), with the same clutch material and you'll know its good to go from the start. Would just take an afternoon on the lift to swap in. Just another option.
Don't have the thread at hand, but it was on team shelby with the PNs and info.
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.
Just out of curiosity, how are they whiney? During cruise, cost and what speeds? I have a installed a set in my car and they Whine during coast between 40 and 50 MPH and a slight whine at during cruise around 80 MPH.