Hi Folks You got me looking! I have a 77 NYB with a 69 K 440 with AVS the orig 440 with LB wouldn't pull my 31' Airstream. I had them Install duel exhaust with only glass packs, It goes down from headers straight back Under the Axle. Have Air shocks and never had a problem with it, was installed in 81 Asa 56,69,77,81