i know it is a 7.5 10 bolt but im about to buye a 3.73 gear and every time i look for gears it says 3.08 and lower carrier or 3.23 and higher carrier what does this mean,which one do i get there is always 2 different 3.73 gears listed.this is for a 2001 z28

 

you need gears for a 3 series carrier. 2 series carriers commonly allow gears of 3.23 and numerically lower. (ex. all 2.73 geared cars have 2 series carriers). Any 7.5" with 3.23's and 3.42's from the factory will have a 3 series carrier. you want a 3 series carrier if you are going to be buying new gears. get the gears for a 3 series carrier. if your car has 2.73's, you will have to buy a 3 series posi unit carrier as well. BTW, if you have an automatic... see what your shifter plate gear indicator thing says. if the palte has a "1" visible on the gear selector thing, you bave 3.23's. if you selector plate thing does not have a "1" labeled and skips straight to "2", then you have 2.73's.

 

I don't believe that shifter having the "1" or not is true about the LS1 cars. Mine has 2.73s and i can put into 1st. And i think i've seen higher gears that are for 2 series carriers.

 

Yes, you can buy higher gears for a 2 series carrier. That is what rockholt454 is trying to say (they list gears for 3.08 and lower (2 series) and 3.23 and higher (3 series). He just did not know what series he needed to buy for. It all depends on what carrier is in his car now.

 

Find the RPO sticker in the console and search for the codes that start with G. The G80 is for the posi and the other will be the ratio. Several listings for them on the net.

 

On a 2K1 the codes are on the drivers side door.

A4
GU2 - 2.73 (2 series)
GU5 - 3.23 (3 series)

M6
GU6 - 3.42 (3 series)