5 on 4 drilled to 5 on 4 1/2.. can it be done?

If you going to send your rear axles out to someone like Moser to get them redrilled and new studs screwed in your going to pay almost as much for the service, plus the shipping costs, as if you'd just bought new axles from them. They have a pretty good deal on stock type 8-3/4 axles with large bolt pattern.

I was looking into getting mine drilled, but just bought the new ones instead. I redrilled the drums myself.

Good luck whatever you do.