9 inch ratio - 3.25 or 3.55?


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I would personally not exceed 3.25 gears without overdrive. I do drive on the highway. I have 2.75 gears which are great for high speed cruising. I turn 2100 @60 with 235/60/15 BFGs. I had driven a 71 Boss 351 with stock 3.91s that a good friend of mine had me work on. I then realized what a bummer it is to cruise any distance on the highway @60-70 mph with the engine screaming away like that. I kept reaching down to shift to a higher gear that just did not exist.
Hi All,

Finally some data. Trans is tagged RUG E3, so 1969 wide ratio. This probably accounts for the car feeling acceptable of the line with the 3.00 rear it currently has.

Tires I am currently running are 215/65-15 at approximately 26" tall. If I changed tire size I'd probably stay in the 26-27 inch range.

Engine setup was mentioned, I know it was rebuilt to be only a little better than stock, no increase in compression and a very mild cam. So for purposes of this in going to say "stock" 351W.

With this updated info, I'm probably looking better with the 3.25 gears, especially with the lower first gear in the transmission?

Thank you to all for your assistance and input, axle is being picked up tonight, work will start later this week.

Best regards,
Thanks it pretty sweet. We will have to see how it does. I was kind of surprised the Q code cars didn’t come with a N case and 31 spline axles. The axle bearings were original and were completely dried out. Also it was just a one legger so that wasn’t going to do. This snowball just keeps getting bigger and bigger.
I went with a 3:25 with a 27 inch tire.
While I was at it I added some Strange 31spline axles. I will be powering these with a 408 Edlebrock headed hydraulic roller motor and a fresh C6.
I’ll probably look at getting a taller and wider tire.
Is that for a 1310 or 1350 u-joint?
Just a suggestion with a 1350 ujoint, go with non greasable vs grease fitting type. With the 1350's larger dimensions it can be challenging to get a grease gun on the zerk fitting.


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Going with the 3.25's, I will be updating the builder today and moving this forward. Thank you all again for your assistance and input. I'll reach if there are any other questions or if I get any inprocess updates.

Best regards,
After much dealing with other things to do involving my homeowners insurance and impending cancellation, and then once past that dealing with new "must-do stuff" that came along, I got back onto this project.

I received the rebuilt rear axle <mostly> ready to install, and the sat on the project until the end of last month. Finally pulled the rear that was in the car and started to install this one. All's been going well except for the new replacement brake lines, which required more work than I would have liked to get into position. Currently waiting on axle flange gaskets, then will finish install and take it out for a spin. I'll update again when that happens.

Best regards and thank you again
Hello Everyone, I hope you all had a great Thanksgiving. Here's another update on this project.

The axle is all hooked up and currently going thru a gentle break-in as requested by the builder. So far, very quiet, and feels better off the line, but really not hammering it until broken in. Definitely revving higher.

Overall, I am happy with the outcome, the car looks better with the correct width axle, I am no longer storing this axle, and I can cross another project off of my list. Win-Win.

Thank you again,

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