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havi · 03-14-2013, 08:02 PM

Had a 3.25:1 9" rear in a '74 F100 w/3sp and 302..... it hauled pretty good! the 9" has some parasitic HP loss, but a built flatty like yours should be no problem to overcome that. However, the jumps in the 39 tranny gears may make a 3.54 better. crashbox 4sp w/3.25's is decent. A T5 w/ 3.54's is dang good. So, doing the mental math, I'd say 3.25's would be ok, except maybe on really big hills.

03-14-2013, 08:02 PM	#13
havi Senior Member Join Date: May 2010 Location: Northshore, MN Posts: 139	Re: Anyone running a 3.25 ratio rear? Had a 3.25:1 9" rear in a '74 F100 w/3sp and 302..... it hauled pretty good! the 9" has some parasitic HP loss, but a built flatty like yours should be no problem to overcome that. However, the jumps in the 39 tranny gears may make a 3.54 better. crashbox 4sp w/3.25's is decent. A T5 w/ 3.54's is dang good. So, doing the mental math, I'd say 3.25's would be ok, except maybe on really big hills. __________________ I'm just an old truck guy trapped in a hotrodder's world.