They used to make a 4.10 set with a thin ring gear. In my last drag car, I went from 4.88 to 4.10. This was with a spool.

I hope they are still made because I need a set. I want to street drive my '67 Belvedere. Original gear was 4.88, I hope to change to 4.10 without having to buy a new carrier and axles. Why new axles? I doubt there are any new 23 spline 3 series carriers so I'd have to change to 35 spline carrier and axles.