My 89 305 TBI camaro RPO code GU2 comes up as 2.73 ratio in the decoder but I'm going to do some work and a 373 upgrade because of damage( a howling noise) But how can you tell if its std or posi, my haynes book does'nt even list GU2...need help ------------------ 89 RS 305 TBI/Hooker catback

also , on a smooth concrete floor both tires will spin and leave a mark---is this posi?

GU2 is indeed a 2.73 ratio. If you want to know if you have a posi just do a burnout on the road. It sounds like you do since both tires spin on a very slick surface.
bsa

Look for code G80, as thats the one for posi. Most RS's dont have posi. Its also possible the previous owner swapped in a new rear end with posi.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

jack the rear so both tires are on the ground after chucking the front wheels. spin one tire with tranny in nuetral and see if the other tire rotates in the same direction. if it spins the opposite direction its an open differential, if they go the same direction its posi.

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former 305 crossfire fuel injection
350 cubes
hooker headers
750 vac secondary
700r4 with shift kit
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"no man with a good car needs to be justified."

thanks for the help. the code on the axle tube is for a std diff. But I have a feeling someone played with it, And now it whines...getting 3:42's put in tommorrow.

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89 RS 305 TBI/Hooker catback