23 spline to 18 spline

We built an 18 spline A body trans that's in my car now with 760hp. It gets street driven all summer and then the slicks go on and drag raced in the fall. Haven't broke it yet with 7000 rpm launches. Before the 18 spline I had a 23 spline behind a 625hp 440 and I never broke that one either all though that one never seen the track with slicks.