You probably already know, but the 1978 hubs aren't noted for being strong enough for large tires. These hubs held up reasonably well with stock size tires.

I think you can use the locking hubs if you keep the hubs locked. I wouldn't recommend this because someone could unlock the hub when the truck is parked and the truck could roll away.

Seems like I heard of someone taking the hubs off a late 80's or early 90's CAD axle and using these newer hubs on the 1970's axles. This swap is susposed to eliminate the hub problems of the 1970's axles and the weaker center of the CAD axles. In other words, you are using the best parts of both axles.

Hopefully someone else will chime in and tell you more about this swap. I'm not real good on the 4x4 stuff.