Originally Posted by 1slow370

courtesy doesn't use standered part numbers they have there own system for the website i had to call for a cross refferance when looking for my axles. Also i have used aftermarket mag nuts before most just come with washers that slide on and off of the nut, they come in a bag when you get the nuts so they don't have to be attached the principle is the same as the oem alluminum wheels that have conical steel seats pressed in ( it's a gm thing). the steel washer is just there to keep the steel nut from scarring the crap out of the nut seat. the ones with the conical steel seats pressed into the wheels for the acorn style nuts also increase the clamping area from the nut to reduce the stress in the wheel that leads to cracking. think of it as a shoulder bolt with a washer, the shank of the bolt aligns the wheel and the washer is there to help in clamping and reduce the stress on the wheel.

On the alluminum alternative, personally i hate alluminum nuts it only takes one getting seized to a stud, cracking/exploding off the wheel in a corner, rounding the crap out of one with an impact removing them if you take it to a shop, to make you really reconsider ever having bought them. Titanium is great though, as well as a heat treated stainless if you are looking for a lower cost alternative to titanium.