I have looked up all off my rpo codes, faq, tech data and didn't find anything about it being 26 or 28. I have an open 2.73. I have been looking for new gears and slp posi and need to know. thank you for the help.

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late model 91 rs
fully loaded t-tops, red leather
paint- gm red and yellow blend (light red)
custom painted 16" Camaro rims
305 tbi 14"x3" O.E, computer chip, accel super stock plug wires
Edelbrock 3" cat-back
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vic_v8@yahoo.com

 

Yes.

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

 

Seriously...

a 91 car has a very high probability of being 28 splines. 88-89 were the changeover years, by 91 the old ones were pretty much all flushed out of stock.

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

 

I checked out a 91 rear today and pulled the axle; it had 26 splines...

 

Doesn't mean much. My 87 had a 10 bolt from an 86 but now has 28 spline axles. Unless you're the original owner don't always assume the car is original. 90-92's should all have 28 spline. Well actually 90 to present have 28 spline but fourth gen axles are longer.

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87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

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

 

My 91 had 26 spline axles and I am in the process of working a deal for a set of 28 splines out of an 88 Trans Am. I think it is the luck of the draw.