Will a rear axle off a 78 Chevy fit my 67 GMC?

[hpcgmc]

I've got a line on a 78 Chevy 1/2 ton pickup that's being parted out. I'm thinking of getting the disc brakes off the front, and the rear axle. I haven't checked the gearing on my 67 GMC, but it's very low gears with heavy duty leaf springs. I assume mine came out of a 3/4 ton truck. My truck is 6 lug, so the rear end will give me 5 lug front and rear.

I read that the front end will be about 1" wider with the 1978 assembly - is the rear end 1" wider also? Do the 5 lug rally wheels stick out an inch to far?

And will the 78 Chevy rear end bolt right in? Can I also use the leaf springs from the 78 Chevy?

Thanks!