ok i know that GM stopped putting the BW(BorgWarner) rearends in the Fbody's in 1989. but while i was under my car today putting my aluminum driveshaft on.i thought i might take a look around and i notice something i hadnt in all the hundreds of times i had been underthere. it says BorgWarner on the bottom of the diff. i am confused. ok my car being a 1990 IROC it should just have the 8.5" GM 10Bolt w/28spline axles. but i am not getting that feeling as of now. i dont know if it has been changed but, i know that the letters on the bottom also read : 023 F9, or it may be 0237 F9. is there anyone that can decode that? thanks everyone in advance.

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Jarrad
1990 IROC-Z L98 350 TPI
TH-700R4
G92- 7.5" 10 Bolt 3.23gears
Bright Red Hardtop/ Grey Custom Interior
5,507 IROC's Hardtops/Ttops; 2,415 5.7L IROC's Produced in 1990

DAILY DRIVER: 1991 S10 2.5L/5SPD WITH CAMARO RIMS

7.5 not 8.5 10 bolt if it has the 10 bolt. If it has a fill plug on the cover, it's a Borg warner 9 bolt(also it will have 9 bolts)

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

According to my Haynes manual, 1990 was the last year for the Borg Warner rear. It has 9 bolts on the cover. Look on the front of the passenger side axle tube. If it has 9EQ, it's a 3.27 Posi, 9ER is a 3.45 Posi.

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1985 Yellow IROC-Z 5.0 HO, T-5 3.73 Torsen, 4 wheel disks
PFCM pads, GTA wheels, Koni yellows, B&M Ripper, Dynomax

[This message has been edited by OLDYELLR (edited April 08, 2001).]

If it has 10 bolts and a metal fill plug on the rear cover then you have a dana 44. 9 bolts and a rubber fill plug is a borgwarner. 10 bolts and a smooth cover is a 7.5/7.625 GM diff. That's all the options available for third gens other than aftermarket diffs.

Chances are that since it says BorgWarner on the bottom then you have a 9 bolt.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
461 Big Block installed and ready for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857 altitude corrected to 11.163
Best MPH on a time slip: 117.87 altitude corrected to 126.10
Altitude corrected rear wheel HP based on power to weight ratio: 476.5
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

ok the rear is smooth. it has ten bolts and it still says BORG WARNER on the bottom. and its casted in.. so wtf?
i am soo confused now..
and sorry about the 8.5" i meant to type 7.5" just like my sig says.

anything more i can look for. and i couldnt make anything out on the axle tube since my flashlight ran out of batteries. oh well will figure those letters out later..

thanks guys. but if anyone else knows whats up, please help!


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Jarrad
1990 IROC-Z L98 350 TPI
TH-700R4
G92- 7.5" 10 Bolt 3.23gears
Bright Red Hardtop/ Grey Custom Interior
5,507 IROC's Hardtops/Ttops; 2,415 5.7L IROC's Produced in 1990

DAILY DRIVER: 1991 S10 2.5L/5SPD WITH CAMARO RIMS

BTTT

Well it sounds like you have a 10-bolt then. BW makes an enormous number of driveline parts of all descriptions for car makers around the world, so it comes as no surprise that they may have cast some housing center sections for GM. Kind of like Q-Jets that say "Carter" on the side.

What do you need to know about it?

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"So many Mustangs, so little time..."
ICON Motorsports

Which 3rd gen got a Dana 44?


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1985 Yellow IROC-Z 5.0 HO, T-5 3.73 Torsen, 4 wheel disks
PFCM pads, GTA wheels, Koni yellows, B&M Ripper, Dynomax

Dana 44 would have to an aftermarket piece.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

BTTT anyone else have an opinion

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Jarrad
1990 IROC-Z L98 350 TPI
TH-700R4
G92- 7.5" 10 Bolt 3.23gears
Bright Red Hardtop/ Grey Custom Interior
5,507 IROC's Hardtops/Ttops; 2,415 5.7L IROC's Produced in 1990

DAILY DRIVER: 1991 S10 2.5L/5SPD WITH CAMARO RIMS

Not necessarily, they used to be available from the GM Performance Parts catalog. A few got Dana 44's as a dealer-installed option. (Like mine )

ok i finally figured it out. the rearend is a GM 10 bolt. i saw a pic of the borgwarner 9bolt. totally different. but i am just assuming that GM had BORG WARNER make the carrier. that is the only conclusion i have come up with.. and thanks everyone!!

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Jarrad
1990 IROC-Z L98 350 TPI
TH-700R4
G92- 7.5" 10 Bolt 3.23gears
Bright Red Hardtop/ Grey Custom Interior
5,507 IROC's Hardtops/Ttops; 2,415 5.7L IROC's Produced in 1990

DAILY DRIVER: 1991 S10 2.5L/5SPD WITH CAMARO RIMS