'06 TJ Wrangler X, stock rear. Bent my right rear axle shaft, got a Superior OEM replacement PA5793A.
Axle goes almost all the way in, and CLUNK - an inch or two short. Old axle goes right back in, no problem, every time.
Superior lists this axle as "direct replacement axle shaft" to "fit seamlessly into your ride." Axle taper closest to splines is in a different location but I assume that's a strength improvement over OE. Spline count is 27 on both, micrometer says splined-section diameter matches up, bearing surfaces same. Axles are same length. Rear axle date code is 2006, should be original.
I'm wondering if you got the wrong side shaft? I don't know 35's so well, but on my 44 the right side and left side are slightly different lengths. I dunno for sure, but maybe worth checking. Is your replacement shaft exactly as long as your original shaft when sitting side by side? Never mind, just saw you said they are same length.
It's a clear fit at the outer bearing; I suspect it's the taper in the shaft closer to the splines than it is on the OE axle. What's confusing me is the whole "stronger than OEM / direct replacement for OEM" aspect, so I give a pass to the different location of the taper. It's otherwise identical.
I searched the whole internet looking for anyone with similar experience -- nothing. The only logical conclusion I have left is that it's misboxed, unless someone here has a better explanation.
Call Superior Axle on Monday and ask them their thoughts on it. They have a sterling (!) reputation for their post-sales support so feel comfortable that they'll get you to where you need to be. If you have any issues after that, PM me as I know their GM who will jump on it.
__________________ When you have a choice, buy American.
I sanitized the axle in preparation for return and noticed slight wear marks from my repeated install attempts at the very edge of the c-clip end. It looked like I had been close. I reinserted the axle and with a flying start applied far more pressure than I am comfortable with when it comes to bearings and differentials: POW-CLANG, it went in. I immediately checked to see if I destroyed anything inside the diff.... ...luckily no.
(Have you ever seen an Abrams tank shell being loaded?)
I've never had to shove an axle that hard and I certainly don't want to make a habit of it.
I've installed several Superior axles - never had a problem - except once.
It wouldn't go in all the way. I didn't want to force it.
Upon close inspection with good magnifying lenses I saw the chamfer on the end of the splines was more blunt than the stock axle. The slight chamfer or taper helps it line up with the side gear's splines.
A quick dressing with a soft wheel in a Dremel to give them a slight taper, then a polish with 800 Grit Emory cloth made it slide in like butter. Just the very ends of the spines.