Anyone else use a crash box sometime?

hi, we ran mopar trans, 3.09 set. had the gears modified by GER . they machined off the small teeth and welded on a pro ring. they had their own sliders and hubs. the splines were very heavy duty. the sliders were bullet proof. you could up shift and down shift this setup. we had this done in 1979. retired the trans in 2009. only maintenance required was
welding up the lugs and machine them down bout every 500 runs, which was bout 5 years of use.