axle swap

[swtman]

I have a '67 gmc 2wd I think a half ton but not sure. It has 6 lug rims on all 4 corners and the guy I bought it from mentioned something about 3/4 ton suspension.Any ideas guys??? It has the trailing arms with coil springs. My real question though is what I can swap into the rear of this truck for an axle. I'm a welder so I can move/change spring perches and other stuff with no problem.It currently has a 3.73 ratio mated to a turbo 350 with no lock-up converter behind a 305 4-barrel v8. I'm thinking maybe 3.08??? Don't need the power, just want to be able to cruise town and the highway and not have such high revs and better fuel milage. I compared axles to my 81 4x4 and the 67 looks to be 2" narrower. Maybe no big deal but I was wondering what axles fit under these trucks with coil springs. Like maybe something a little newer?? Thought probably someone on here would know some options of what works and doesn't. Would probably consider swapping to 5 lug axle and changing front to match. Any ideas guys??? Any help would be greatly appreciated!!!