1977-PREVIOUS F350, F250 snowfighter: low pinion dana 60, very weak.....
1978-1979 F350, F250 snowfighter: high pinion dana 60, kingpins, 35 spline outters, 30 spline inners, internally splined lockout hubs
1980-1985 F350/F250: high pinion TTB dana 50
1986-1991 F350: solid high pinion dana 60, king pins, 35 spline outers, 30 spline inners, internally splined lockout hubs, different spring spacing that 78/79 axle
1986-1989 F250: TTB dana 44HD/ TTB dana 50, both high pinion
1991-1997 F350: solid dana 50/solid dana 60, 50 hase smaller ring gear and axle shafts than 60
1990-1997 F250: TTB dana 50, high pinion
1999-2001 f250 and f350 SRW have dana 50 high pinion, metric pattern
1999-2001 f350 DRW have dana 60 front diff
2002 and up f250, f350 and f350 DRW have the dana 60 front diff.
1999-2008 F350: solid dana 60, high pinion, metric pattern
and even then,..believe it or not,...the front depends on build date,..and of course what ever they had laying around....seriously,..if the truck was supposed to get a D50,..but they didn't have any in stock at the time,..they threw in a D60
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