I have a 87 camaro v6 5 speed and am trying to figure out what rear end gears I have. I put it into the calculator on the main page and here is what I'm coming up with.

Calculated Gear Ratio (Trans. gear multiplied by rear end gear)
Tire Radius RPM MPH =Gear Ratio
12.5 2500 75 = 2.65731

Rear end gear (relative to variables of calculated gear ratio equation)
Calculated gear ratio Transmission gear =Rear end gear
2.65731 0.73 3.6401


Would this mean I have 3.73 gears? or what is the closest gear ratio that came in an 87 v6? (Oh, my car was originally a 700R4 but if Im not mistaken the 87 autos and sticks came with the same rear gear)

What is the closest gear ratio that came in a posi rear?

 

You should probably post stuff like this in the Drivetrain forum. At any rate, unless someone changed the rear gears, you've got a 3.42.

https://www.thirdgen.org/newdesign/tech/techdb.shtml

Not sure what models came with posi.

 

some v8's had it, its highly unlikely that your car was optioned with a posi rearend

 

Then there's the check-it-the-fun-way method. Jack up a rear wheel, put the trans in neutral, turn the rear wheel 720*, or 2 complete rotations, and count the number of times the driveshaft turns.

 

nice method

 

Can also run the axle's manufacturing code against the Haynes 82-92 Camaro or 82-92 Firebird manual. They list a lot of codes but every once in a while there will be a code that's not in the book. (I did a LOT of junkyard crawling in my day ) Watch out for those huge brown spiders; they like the safe damp mud underneath an axle, usually they hang out above the axle or inside the tire. I screamed like a little girl when I took my j/yard rear axle's rotor off and saw a HUGE- but dead- spider in it!