You could probably get away with running one locked. I think Aussie may be one of your only choices for a locker though... don't quote me on that. The D44a is weaker and if you do much with rocks, you can punch holes in the diff easier than an iron center section. From what I have read on the 44a, they like to chew bearings too. So, yes, you could lock the 44a, but your money might be best spent on a different axle.