question on the 7.5 rear

[90dpscoupe]

Oldman, i think u just answered my question, my friends 85 coupe, was a ex-4banger, and we are not sure if its an 8.8 or 7.5, but i was gonna ask about a "clunking" noise we hear? it does have e.t. streets on the back, and i was sure those stickies would break a 7.5 pretty quick? also has alum d/s, what you think? how can i tell?...thnx

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90 lx coupe: 175k miles, steeda water pump pully, hurst shifter, Mac cold air fenderwell, accel supercoil, ADS chip, aluminum D/S, Black magic fan, 3.27grs.
Best time: 13.9116(on 225/60/15 firehawks)
Best mph: 98.17
Best 60': 1.9607

next mods: subframes, mac h-pipe