I think it was 83-84 when mopar started running Q jets, from what I heard the plan that built T quads burned down taking the tooling with it.

One of my Dads friends bought a 85 D150 with a 318-4 833OD and he was surprised by the Q jet, after riding in it my Dad ordered a new D100 with a 318-4 but it was late in the year so it came in as an '86 with a 318-2, he refused the truck when it came in so they installed a performer intake with a 85 spec Q jet, air cleaner, throttle and KD linkage etc.