Hello. If the rear end is in a car take it into a parking lot and scorch the tires, then get out and count the stripes on the pavement.Two is posi, one is not.Posi on an 8inch rear end is very rare.A lot of people will tell you that it wasn't even available on 8inch rear ends, but it was.Hope that helps.
Yeah, there's a real easy way.
Jack up the rear end. Make sure both wheels are off the ground. Place jack stands under the car!!! Turn one of the wheels with your hand. Look at the other wheel. If the two wheels turn in the SAME direction, it's a Posi; if the two wheels turn in OPPOSITE directions then it's a Non-Posi ( open rear).
if it's rare i won't bother checking. i didn't know how common it was.
i might buy an old rear end to swap into my 66 200ci mustang. i bought a 302 to drop in. the 7.5 or 7.25 " is making some noise. so looking forward to the 302 install in the future i figure i should swap in an 8" to fix the 7" instead of fixing the 7". i have a 200ci with a C4 tranny. if i swap in an 8" rear end for the current 7" will the szme drive shaft work? does the U joint on that end need to change?
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