Which 9" rear end would you choose

If you run the 3:25 with stock 14 inch rims and tire height you will have a 3:25. That gear was a factory install with C4. If your car came with a higher gear your speedometer will be off but that is fixable with a new speedo drive gear.
I say for what you want to do with your car go with the 3:25. You can run the track scene just for kicks with anything. It will serve you better for around town cruising and freeway driving.
If it was a 3:50, it would be a no brain er.
BTW, you're not suppose to race on the street anyway.

1bad6t, I bet those 4:11's you originally had in there really made that thing roar at 80mph.

I run 4.10's with my C4 and 275 / 60 x 15 and Reasonable highway cruising isn't bad.... I would want to run 85 all day but 55-65 is totaly tolerable.

Big Heavy car and a tiny little motor needs gear to get anything close to respectable performance.

rtyler, I had a 4.56 originally. I could cross a 4 lane intersection and stretch all 4 gears. This is with 195/60/15 tires

Originally Posted by walaby

Took me a few times to read, but I think what he's saying (RCode, please confirm).

If I bought the 3.25, and drove it with 14", it would be something more than 3.25 (mebbe not 3.89). If I put 15's on, it would be less than 3.25

If, I went with 3.89 and 14's, then I would be more than 3.89, and I put 15's on, I would bring it closer to 3.25 than 3.89...

Did I get that correct RCode, or am I all jacked up. After I typed it, Im not sure anymore!

You are correct my friend . Maybe instead of useing lower and higher I should of called the ratio of what it is but look at it like this .

Like a 10 speed bicycle , same difference somewhat . When you shift up , a taller larger gear or bigger it gets harder to pedel in reality you just threw on a larger tire on the rear . On top end it will go a higher speed each time you get larger . A low gear will pedel easy , get there faster but no speed on top end . Same as a baseball beside a basketball . Roll or push both side by side , basketball naturally goes fauther but is harder to push . Baseball easy to push but does not travel far . Now same with car tires . Larger tire say a 33 inch high with a 410 gear in a car say rpms will run around 3500 in 4th gear , place a 28 inch tire your rpms at same speed shoots to 4500 . Hope ya understand it is simple

Tell ya what , if you could place say a baseball on your rear of car it would run say 15 mph wide open . Put the basketball , large on and you could ride fast but slow on take-off .

I 'm just saying with a low gear such as a 411 with 14 inch rims and small tires you cannot drive fast and your motor is wound high . Place 15s on with 33s with same 411 you see a big change , slows rpms down same as if you placed a 300 gear in . Just easier to change tire size and differ rims to have both worlds with less work . As for what rear ya want thats up to you if you understand the cosmetics of tire size . As for the speedo change any gear change will throw off your speedo from factoy . As stated below change gear on cable if ya like but tire switch rechanges speedo again . Qure for that is go by your tach . Have a friend follow you and cut his lights on behind you when you reach 55 mph , then look at tach to see rpms . Any speed you want to read tach like nascar when going in pits . They have no speedometer , use tach .

Originally Posted by RickRacer

Rcode, you kind of lost me on the higher and lower part pertaining to gears. When you say higher you mean around 3.00 gear and lower would mean around 3.89 or so? If I'm understanding you right then, my 66 has around 2.73 or whatever in it now with 14" stock rims and tires. By me switching over to 15" rims and taller tires it would raise my gear ratio to say around 2.50 or whatever? If that's true then I think I'll be making a gear change myself.....maybe a 3.50 would be in order with those 15" tires.

Yup you are correct also . Ya'll got it . All it takes is thinking . Now ya got that tell ya what I do in race car . I use a 588 with 35 inch tall tires . When I want lower gear I change to a 618 or so . In racing I want a high tire as wide as possible . More tire , more traction on pavement . I also run a doug nash and richmond 4 speed which is easy to gear lower . I take tranny out from inside car in about 10 mins , remove 2 bolts and slide pin out of gear box . Pull gear out and slide in any size . Return pin and 2 bolts , return tranny . All that in 20 mins or so .