[jim_howard_pdx]

I've got a great answer for you, but you need to think this through and determine the actual purpose of the car, how the car is driven, and how bad you want to blister the competition.

First AND THIS IS CRITICAL, It makes NO sense to run any gear set without a strong and functional posi system. If you have a drag car, you want a spool or at least a mini until you can afford a good spool.

If you have a street/highway/ or autocross car you need a Detroit Locker, a PowerTrax, or a limited slip posi unit. If you do not have one, wait to install your gears. Cause trying to launch with only one tire supplying traction will kill you, and guys like me will bust their guts laughing at you.

If you have a posi, take it out and have it rebuilt. If it is a spring type unit, have the springs removed and shim the clutch pack to 140-160 ft pounds of pressure. That way the posi will be a torque sensing differential. I will explain this to you later if you do not understand. You can call Currie rearends and they will ship you everything you need to perform this modification. TSD differentials last a lot longer than spring clutch posi units, and they supply traction as a function of torque, so they do not waste the clutches when you really don't need posi at all.

Slicks or Street slicks are important with 3.73 gears and steeper. As the engine turns 4 times per tire turn, the engine reaches maximum torque levels VERY QUICKLY. So on standard tires you will sit there in a cloud of smoke. And I will laugh even harder.

Now, look at your engine. What is your top rpm at this time? Will it improve soon? In my case, the 358 Windsor engine is balanced and blueprinted to run 7k rpm. My cam is good to 6.5K rpm. So if I want to be at 6500 rpm when I hit the trap speed zone of the quarter mile, I would want a 4.30 gear. If you run 7k rpm you could use a 4.40 gear or even a 4.50 gear.

Your top mph will go down slightly as you go lower and lower on the gear ratio. But your ET's will go lower and lower too, so it is a compromise.

If the car is dragged a lot, then I would go 4.30 with a TSD Posi, Locker, or Spool. If it is highway and street car I would go 4.10.

I would not go 3.73 under any circumstance because that is where the majority of your competition will run. The 4.10s will have SIGNIFICANT extra launch capability, and with a small block, it will allow you to rev through the gears easier. It puts LESS load on your bearings and may reduce your engines propensity to detonate or predetonate.

So I hope this helps. I plan on running 4.30's on the track next year. My computer says my package will cut an 11.90 on gasoline and an 11.15 on a 200hp squirt of NOS. These are awesome times for a street/highway car with a autocross suspension.

Plus my 9" ford rearend allows me to swap gear sets in under 2 hours with basic hand tools. So I will keep my 3.25's should I want to run the silver state classic in the 150 mph bracket.

Good luck, I vote for 4.10s or steeper!!!!