I can't seem to find any concrete testimonial on which would be best for my applications. The car is going to be a street/strip car with occasional road course use. The rear end will be a 12 bolt with a 3.73 but depending on which trans ratio I go with I may get a 4.10 instead. Motor will be a 525hp crate LS3.

 

Are you going with the T56 Magnum?
The closer ratio box is probably a better match for the build.
5th & 6th can be changed at a later time if you decide you want more OD.

 

for what its worth I would not go with the 12bolt and a 6-speed.

 

The T56 comes with a few different gear sets. So its hard to say without knowing what T56 you are getting.

My T56 uses the M28 gear set. So its pretty short in 1st.

3.36, 2.07, 1.35, 1, .80, .63 ratios.

What road courses are you going to run? You may want to avoid the 4.10's if you are going to see extreme speeds that require the use of 5th or 6th gear. This is because your drive-shaft will be operating at over driven speeds.

With my M28 gearing, a 3.23 final drive, and a 7000rpm rev-limit 4th tops out around 160mph @ 6800rpm, and 200mph in 5th.

If I went with 4.10's it would mean I'd be spinning the driveshaft 8600rpm in 5th gear @ 160mph.

At Road America where I would be running I just am not comfortable with the idea of spinning the driveshaft that fast.

So the most I'd do is probably a 3.73. It would keep the driveshaft speeds down to a safer level.

 

Not to jack this thread, but why?