A GM catalog will be worthless in this situation. You will probably have to remove the hub and remove a stud to get some measurements. The Euclid catalog is very helpful in getting longer studs. If you can find s parts house that still has a Euclid catalog and has some old enough to read it, you can probably find something. If you can't find anything, figure out if it is single or double ended and the diameter of the serration if it is single ended. Adding an inch or more to the present stud will allow for aluminums. Post the dimensions and I will get a Euclid part number.

https://photos.app.goo.gl/pSSxrKBSxVU4QWpp8