Robert, I'll take a couple of photos of how they fit the axles and post them up this evening. Essentially, there is a 1/8" gap on the sides (so the u-bolt only touches the top of the axle). Did you just have an issue with the ends being too wide, or was the entire bolt too wide (meaning the sides of the u did not contact the sides of the axle, as is my case? The stock Nissan u-bolts are uniformly 4.25" wide as measured from the outside to the outside, while my PRG bolts were uniformly 4.5" wide. If I made them fit, I'm concerned that I'd be exerting a ton of force on just a small portion of the top of the axle, rather than all around the top half in a semi-circle like the stock bolts appear to do. I don't know that I'd call this custom. The springs and such are definitely mass produced aftermarket parts, and the u-bolts, even if they have to be custom made, should just be slightly longer copies of the OEM u-bolts.
I'll also post some photos showing the u-bolts Nisstec sends out vs. these for the benefit of future purchasers. I don't have the Nisstec u-bolts in my hands yet, so there's no guarantee they won't have the same issue (though they told me on the phone they are the same width as stock).