I have not checked it yet but I was under the impression it was 26 spline.That late 80's Camaro posi will need 28 spline axles. Why not just add the Torsen posi with Moser axles and a girdle cover on your current rear end? It is easy, you just need to shim for proper backlash. Reuse the bearings on the Torsen posi, it they are in good shape and have the matching cups. If you want to blow money you will never get back, go for it.