https://randys-transmissions.com/ma...ker-for-dana-60-4-10-down-40-spline.html

Also, there is / was an Eaton P/N 225SL193B, 40-spline Detroit locker.

Anyone ever seen or used one of these ?

I'm wondering if it is a 35-spline unit with just different side gears, maybe Dana 80 side gears ?