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I found a great deal on a 95 L99 Caprice the guy put in a Polce carear end but he does not know what size gears? It has the big drum brakes so I am guessing ts from a 91-93 Police car what option ratios did they have? Its def a 8.5 in one so I know he i telling the truth.Did any 94-96 9c1 police rear ends come with big drum brakes?
 

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i'm not too sure of all the options in rear ends for any of the years. but i know the best way to tell the gears in a rear would be to raise the back end with the back wheels off the ground and put the car in neutral and spin the drive shaft one full rotation and count how many times the back wheels spin.
 

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i'm not too sure of all the options in rear ends for any of the years. but i know the best way to tell the gears in a rear would be to raise the back end with the back wheels off the ground and put the car in neutral and spin the drive shaft one full rotation and count how many times the back wheels spin.
It would be easier to turn the wheel 1 turn and count the turns of the driveshaft. It will have a tag hanging off of the lower passenger side at the cover if it is a posi.
 

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3.42's were optional in those years. I forget what they came with normally tho. It will say the axle codes in a FSM. I don't have one for a 91-93... All the 94-96 Police cars had rear disc brakes. But that doesn't mean it couldn't be from a taxi, or a Caprice with the towing package, and he is saying they were from a police car, hoping you don't know the difference. Did he have the PCM adjusted for the different ratio? Or is it off. If it had a tach, and you ran down the highway, and figured what RPM it was running, and tire size, you can figure out what ratio it is.
 

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It would be easier to turn the wheel 1 turn and count the turns of the driveshaft.
Hardly. So I have like... 1/3 of a turn of the driveshaft, and one turn of the rear tires... that means it's... like a 3.00 gear ratio? What's easier than that, is to turn the driveshaft 10 tims, and then count the number of times the tires go around. Gives you a MUCH more acurate output. Think about it. The tires go around, not quite 30 times... 2.93 ratio. lil over 30 times, 3.08 ratio... lil over 32 times, 3.23 ratio. See where I'm going with that? :)
 
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I found a great deal on a 95 L99 Caprice the guy put in a Polce carear end but he does not know what size gears? It has the big drum brakes so I am guessing ts from a 91-93 Police car what option ratios did they have? Its def a 8.5 in one so I know he i telling the truth.Did any 94-96 9c1 police rear ends come with big drum brakes?
all 9c1 from 94 to 96 had rear disc ,non 9c1 caprice classics with L99 had small rear drums and non 9c1 caprice classic with Lt1 had HD 11" rear drums and 2.93 radio with posi rear. thats what you might have if it has rear hd drums.
 

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If there is ANY chance you can read the code stamped on the forward side of the right (passenger side) axle tube, it will be possible to tell what the axle was originally built as, whether it's still stock or not.

Here are the 93 codes for 8.5" Chevy sedans as listed in 93 FSM: (may or may not match information in GM Parts Book below)

(sedan/taxi)
Standard (open diff) 4LG GU4 3.08 ratio / Limited slip 4NC

(LTZ)
Standard 4ZH GM8 2.56 ratio / LS 4ZL

(police)
Standard 4ZK GU6 3.42 ratio / LS 4ZJ

For complete list of 91-96 axle codes, see the charts in the Online B-body Parts Book - Pages 881 to 883
 
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