I have a 1966 coupe with a 351w a 9" rearend and a t5 transmission. I want something that will be real quick off the line. I don't drive on the highway much so that doesn't really matter. What gears would you suggest?
that's not a question we can answer for you, but we can give you suggestions. with a lower gear(higher numerically) you will get better acceleration, it will rev faster, but at the expense of fuel mileage and traction. it depends on what you can tolerate, some people wont go higher than a 3.50 cause they say it makes too much noise and revs too high but with that OD 5th gear you can get away with a lower rear gear. i recommend a something between a 3.90 and 4.56, if the car is going to see any competition you should calculate track length, rear gear and tire ratios for optimum RPM and maximum performance.
If you are going to have fun taking it to the drags and you really want to do well then 3.90's or 4.11's might be your best choice.
But if traction off the line is a problem then 3.90's will just make it worse.
I have 3.00's in my 67 with a 351w and traction is a rarity. Of course, a traction lock would greatly help matters but who's counting . I am planning to go to a 3.40 or 3.55 rear end when I have the money to do so. With my gearing now, I am doing 78mph at 2000rpm on the freeway in 5th gear, so changing to a lower gear for me will make it less luggy in 5th, which is good.
My T5Z has a 2.95 first gear, coupled with my 3.89 rear is all (and more) first gear you could ever use, really too short-ish for the street. Other T5's have different 1st gear ratios, up to 3.35 as I recall.