going from 3.42's to 3.73's
 

Is there any notable difference going from stock 3.42 to 3.73's in an m6 bolt-on camaro Z.

Probable not much...might as well go with 4.10s if your going to do the swap. They won't hurt your gas mileage that much if that is your concern.

I agree with zracer, not much of a difference going to the 3.73's..... 4.10's mate well with the M6 and are flat out seat of the pants fun yet allow for fairly normal driving as well.

m6-4.10s
a4-3.73s

3.73s are more durable than the 4.10s when using a 7.5" rearend, due to thinner gear teeth on the 4.10s. Will affect your shift points on track, depending how you use the car (road race or autox).

i have heard that the thinner gears on the 4.10s arent really that big of a deal. i say go with them.

I wouldnt waste time/money with 3.73 in a 6 speed. Its hard to over gear a 6 speed. The 6th gear kinda negates the axle ratio to a certain extent.

4.30 is a good gear for a 6 speed. You can cross the traps in 3rd in the 1/8th and it will wind out 4th real good in the 1/4. If you are going to spray 4.30 would be a lil much unless you go to a 28" tire.

plus one on the 410's

Agreed. I'm spoiled to the 4.10's. It's one of my favorite mod's for the LS1 fbody.

I have the M6 with 4.10's car does 2100RPM at 80MPH and 1800 at 70MPH. For sure, get the 4.10's. 3.73's will make only a small deferance.

i have a question do i have a m6 with mostly bolt on and i was thinking about getting a tune. Then later this summer i was going to get some 4.10 gears would i need a tune again for the gears or not?

How can you tell what gears you have in your car? From what scidav87 said with his 4.10s as far as 1800 at 70MPH is what mine does as well. Last week I found out I have Koni 4/4 on it - didnt have that one listed on the details. I keep finding out more about SS that I bought off of someone two years ago.

With m6 gears shouldn't affect the tune.

Need to fix the speedometer.

If you have a T56 from a 98-02 LS-1 fbody and your doing 1800-1850 at 70 in 6th, you have 4.10's. The T56 trannys from LT-1 cars have a different gearing, i'm near possitive. So the RPMs would be different. Just pull your rear cover off and count the teeth, and divide the #. 41 tooth ring with 10 tooth pinion = 4.10

10 bolts cant handle a hard launch with 4.10s (if at all haha) and 3.73s give you better shift points and are ebtter for street racing, 4.10s are the M6's best friend though:D

or just lift the rear up and spin the tires.

What about 3.90's? Seems like that would be a good medium if you didn't want a 4.10

I've had a few sets of gears..
3.42 -> 3.73 (no more low end bog but no huge gain)
3.73 -> 3.90 (def can tell there's some gear in there/hooking on street is trickier)
3.90 -> 4.10 (1st gear is very short/shift points def change)

All in all the 3.90's were my fav w/ stock size tires (275/40/17)
*I lost mph when I went w/ 28" tires so settled on 4.10's
But also have stroker motor now and shift much higher than prev bolt-on

cdubbzz were you running an A4 or M6 with the 3.90's? What were your cruising RPMS as well?