Striaght axle is well worth if if you want suspension travle off road, im running a luv frame on the chevette... I used wagoneer axles, which are a little wider and give it a nice stance, with 55-75 cj leaf springs, if you use that set up, youll need to weld a piece of 2x3 square tubign on the side of your frame, where the rar spring hanger goes, and a piece at the front stickin out past the frame about 2 inches. It fits rather nicely, and is the perfect width that way, so you dotn ahve to move the spring perches on a wagoneer axle.
DO NOT GET THORNBIRDs... they are usless, the mud build sup terrible, not good on rocks, they are slicker than crap, not even good on wet roads. Or sand either. I speak from exsperiance.
Here is a picture of what I mean with the 2x3 tubing.
Just so you know, this setupt and why that leaf sprign is broke. It broke becuase i was running long shackles, and I snagged the front on a rock.