modern dually rear end question-selection questions

i,am going to install a modern dually rear end in my 1972 chevy 1 ton dually truck because of parts availability for the old eaton rears is getting very limited. anyway does anybody know when ( model years ) gm, ford & dodge went to the 8 lug metric bolt pattern ? i need a 14 bolt, dana 70 or preferably dana 80 dually rear end that has the 8 lug on 6.5" bolt circle . i,d really like the dana 80 as it is rear disc brakes. any tips would be appreciated.
bob

F-Superdutys from ? to 97 have 10 lugnuts on their Dana 80's

Superduty's from 99-up have the metric bolt pattern, which has changed once or twice...

thanks cap

Bob, you can put disc brakes on either a 14bolt or a 70 very easily. Many Chevy duallys are 70's...... but if you can find one, I think the extra pinion bearing makes the 14bolt the better choice.