Slick 60's

Guys need some of your knowledge here. I am looking at purchasing a 1980's Dana 61 from a Ford F250 or 1980's Dana 70 from a Ford E250 with 3.07 gears to narrow and put under my 1966 F250. I have measured and both axles should narrow up fine and fit under my 1966 F250. The only problem is I would like to put a posi-traction unit in the narrowed axles but I cannot find one for the Dana 61 with 3.07 gears. I do see posi-traction units listed for the Dana 70 but I want to make sure they will work with the 3.07 gears ok. I'm trying to sort out as many details before moving forward with this swap. Any advice would be appreciated. Thanks!

the gears have no affect to the posi unit. you would be fine installing it in the my question is the gear for the truck. there are ratio caculators online. to see the correct gear for your slick.