Update: I finally got a good look at the axle. The spindle didn't shear, the welds broke. I have a square tube axle with the spindle welded on top. In order to use the 4 lug rims, mount
brakes, and keep the trailer at the same height, the end of the axle was cut back at a 45 degree angle and left open. The spindle itself doesn't look to be as long as the replacements I looked at in the shop. Just not enough good surfaces to weld to, plus the cut back axle may have flexed. I ordered a 3500lb axle, new
brakes, and new 5 lug rims. Oh, shocks too. Trying to find a local welder to fabricate a heftier axle to fit the brakes and rims was just too hard. Lots of $$ but at least I'll have standard equipment. I'm hoping the guy in WI will pay for some/all of it to keep his good reputation.