Axle swap

[67chevy1]

I have 2-12 bolt rear ends 1 is a 6 lug under a 67 short bed don't think original. The other under a 68 I know it's not original as it is a 5 lug. I bought the truck for parts only. What's the chances of being able to swap axles and leave the housings. I wouldn't mind changing the whole rear ends out other than the fact that the one that I was going to use has already been blasted powder coated and new breaks. The 5 lug axle is 30 spline and 30" to the back side of the hub machined area. I've also put every new part in the brake system on the one I'm using.