Question regarding gear swaps
 

Please excuse me for jumping in as a newbie with a question. But i run an 1985 Trans Am rear axle in my 48 Buick and need some help, you guys are the experts on this stuff so here I am.

Question 1, is there anyway to I.D. the axle to determine the current ratio? I run 9 inch axles in my other cars and Im not used to the GM stuff.

It seems there is a 2 series carrier and a 3 series carrier, the 3 series being used for the 3.23 and larger stuff. Can you tell me if my axle would have the 2 or 3 series carrier?

Any guesses as to what ratio I currently have would be appreciated, I didnt write the vin info down when I swiped the axle out of the boneyard.

I currently have a gear whine and need to replace the gears and I would like to make sure I have the lowest (numerically) numbered gears as possible. Until I determine the carrier size, i cant order the lower 3.08 gears.

Thanks in advance for your help.

If you wanna see the setup, its on my site, www.hotrodsbyglen.com

there is a way to check the ratrio of the gears by turning the driveshaft. let me see if i can remember...i think this is right... jack the rear up and put a stripe of tape on the inside of the tire going from the rim to the edge of the tire. now turn the tire until the tape is at the 12 o clock position. now crawl under the car:( and put a line on the rear of the driveshaft and rearend housing with a piece of chalk. this line should be straight. turn the driveshaft 360 degrees while watching the tape on the wheel. count how many complete 360 degree roations it makes for one 360 degree rotation of the driveshaft. if it turn 3 1/4 times then there are 3.23 's in it. if the tape is just past the 3rd rotation then there is 3.08's in it and so on. Please do not quote me on this procedure. I am not 100% sure this is the right way of doing this. If someone reading ths knows the correct way of if I am right please respond.

You have it backwards. It's the number of driveshaft turns it takes to make one complete wheel rotation.

You can also take the diff cover off and divide the number of ring gear teeth by the number of pinion gear teeth.

If the ratio is 3.23 or higher, its a 3-series...if it's 3.08 or lower, it's a 2-series.