So I understand a little about the the gearing works ratio wise etc. I'm going to have 4.11 diff gears and currently have a 904 on my 225. Was thinking of switching possibly to a 4spd manual. And I'm wondering this.

Is there a way I can change the ratio of the fourth gear to only be a highway gear? So when I am on the highway I can shift into that gear and be at the bottom of the revs?

The car is currently a 3 speed and I don't mind having only 3 gears for street I don't use it a lot and I find it fun.

But I want a fourth gear of some ratio (unsure what) that'll put me at the lowest possible revs of the car, or is this just a stupid idea?

Thanks.

To do that with 4.11s in the back you would need overdrive.

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Dave

1977 d-200 crew cab ex-army pickup wants it's /6 back
1962 Valiant 2 door, 170, three on the tree
1972 d-100 parts truck
80 volare wagon now a parts car

Your differential gear choice would be good with an overdrive 833, I agree.

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/6 '67 Barracuda convertible, electronic ignition, 4-OD, street cam, SBP KH discs, 3.55 SG 7.25" 1" t-bars. Bilstein.
340 '67 fastback, Doug Nash 5-speed.
1988 Toyota pickup work truck

Anyone care to expand on that...? That's like a 833A gearbox or something similar I believe? But what exactly do you mean by OD?

To pull this off you will need a bellhousing and a 1975-1980 A-833 Overdrive Transmission...the 4.11 rear gear and .73 OD gear would put you in the same rpm range as having a 904 tranny and 2.94 rear gear approximately...

I have done this with a steeper gear (4.56 x OD = 3.3 equivalent final gearing...)...in my heavier duster.

-d.Idiot

i just put 4.10 limitedslip in my 80 d150 from a 3.55 open behind a-833 ....love it