1970 DUSTER 440 4spd 8 3/4 posi

The breaks run '63-'66, '67, '68-'72, and '73-'76.
'63-'66 used a different center link for /6s and V8s. Also had the small sector steering box. '68-'72 used the small sector steering box as well and the same center link for /6s or V8s. The '67 used its own idler arm so I put it in its own category. Every thing else was the same as '68-'72. '73-'76 used the large sector steering box and linkage was the same whether /6 or V8. I think the pitman arm was different for power or manual steering in those years. NAPA has a different part number for each application.
Good rule of thumb, use the same year span linkage as the year of your steering box. The center link swap is only needed if you are dealing with a '63-'66. In 1976 I dropped a 440 into a '76 Feather Duster with no steering changes and no clearance problems. Still a nose heavy pig though. Just make sure the oil pan has the notch for idler arm clearance.
Hope this helps.