Head fire rings

[DVT873]

Interesting. My exposure was all medium duty, max gross was usually maybe 60k. By the mid 90's almost everything had gone auto, mostly Allison. Did get into some issues with wide vs close ratio. Fall on their face between 3rd and 4th with wide ratio. Taller gear as in 5.57 vs 4.56 gave better launch and stronger pulling thru the midrange. Have never quite got my head wrapped around "torque converter effect" but it is a factor. Above 30K usually is a 3000 series. 2000,3000 and 4000 all lock-up.
Thanks