How do i tell what g/r my diff has without pulling it apart?
I have a 1984 Trans-Am, L69, w/ WS6 package and 700r4 trans.

Thank in advance.

By pulling it apart.

There is no substitute. All else is guessing.

most all of these were 3.73

i had one just like it too

but it might possibly be something else

hard to say if someone changed it over the years too

pull the cover to be positively sure

or guesstimate by your rpm at a given speed and with your tire height with an online calculator

do a google search for them

i dont want to take the cover off because the filler plug has had the square hole chewed up so if i loose all the oil how am i gona fill it up again without taking the plug out?

so if im in 4th gear doing 100Kmph @ 2,200RPM with 215/65R15's how do i use that to get the g/r?

That all depends on how far off your tach is, and the ACTUAL MEASURED radius of your tires from the center of the wheels to the ground. Which is NOT the same as (215 x .65 / 25.4) + 7.5, you can be sure of that.

As I said, the best you can do without actually looking at it, is guess.

The right thing to do is to drill the center of the remains of the plug out, and use a BIG easy-out on it. Then replace it with a brass one so that doesn't happen again.

Oh, and don't forget check out what gears are in it, while you're fixing the damage.

I got an Speco 5" it is a $280AUD tach so id say it is showing the right RPMs

I guess it will be one of the jobs while the car is off the road, i got to drop the fuel tank so ill do it while im under there.

While im here it also has a humming noise coming from the rear of the car but it is only under load or on HOT days, oh and i only get 1 black line when i plant it, I thought these cars had LSD?

it could still be a lsd, just burnt up. Another reason to pull it apart.

look in your center consel on the bottom side of the lid. Your RPO sheet should be there. If it says GT4 then you have 3.73

it is not the original c/console lid and there is no tag in sight any where.

OH 1 thing if the diff g/r is changed that would screw up the speedo reading wouldent it?