I have a 1984 LG4 with a 305 in it, what are the chances that I have a posi rear? how would I go about checking to see if i have one? is it in my vin?

 

That info is not in the VIN.

I would rate the likelihood of it having a posi as somewhere between slim and none, and Slim just left town. Or at least having come with one; somebody could have put one in there at some point in the car's life. More than likely, that car would have come with the worst possible gear for performance that was offered in these cars, the 2.73; and no posi. It's an excellent area to consider for an upgrade, maybe even before doing any (yes, I said any) motor mods.

The easiest way to tell is to take off the cover and look. A posi has clutches inside the carrier, a one-wheel-peel will have only some little gears.

Have you changed your rear end fluid, and put in fresh synthetic lube so you can get your extra mile or 2 a gallon? If not, you need to take the cover off anyway, so just look while you're replacing the fluid.

 

or you could just do a burnout and see if both wheels light up or not (thats the most fun way to tell).

 

the best way to tell is by option codes.my car is an RS W/305 auto and it has a factory posi.just look for the option code G80 on your RPO label(option code label in glove box)

 

Another easy way is to jack up the back of the car and spin one wheel with your hand. If the opposite wheel spins the opposite direction, you don't have posi, if it spins the same direction, you have posi.

 

well guys i checked out my rpo codes and i have a tmh 700 r4 tranny and limited slip with a 3:08 gear ratio, hey its better than 2:73 right