In what model year did the three point seatbelt first appear in Ford pickups?

 

I think it was sometime in the early 70's but don't know the year.

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2000 F150 XLT Reg. cab
4.6 Triton Engine
4x2 3.55 rear end gear
sliding rear window
automatic keyless entry
white styleside short box

 

Thanks. I'm looking for an old truck but the three point seatbelt is a must. I didn't really want to start off with a seller on the phone by asking a stupid question(I like to finish with a stupid question).
Thanks again.