since drifting involves limited traction, your diffs should not be set up as your would normally set them up with a grip setup. most people have their rear diffs either tightened. most of it is personal driving style, but if you find yourself spinning out a lot, try tightening the rear diffs. just beware that with rubber tires, a locked rear diff will cause a lot of rear tire wear (especially if you use a locked diff in a grip setup... if you are drifting with abs, don't worry)

if you want to lock a diff temporarily, you can either tighten the spring all the way if you have ball diff, or if you have a gear diff, lock the inner planetary gears with silly putty. for a permanent locked diff, use jb weld or any epoxy you can get your hands on. i would recommend doing the temporary fix first, because once you permanently lock them, there is no going back.

hope this helps. happy drifting!