Posi unit for 87 Blazer - S-10 Forum
 
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post #1 of 21 Old 03-17-2019, 03:25 PM Thread Starter
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Posi unit for 87 Blazer

I picked up a 87 Blazer 2wd has 350/700r4 308 gears. I would like to out a posi traction unit in it but don't want to spend a lot because down the road I will probably but a better housing in the truck.

I'm told it should have a 7.5 rear end in it. What options is there ?

I came across a used unit out of a newer 90's Camaro with very low use are these the same ?

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post #2 of 21 Old 03-17-2019, 03:28 PM
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Re: Posi unit for 87 Blazer

theres about 3 styles(manufacturers) of 7.5 differentials

do you have any idea which it is?
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post #3 of 21 Old 03-17-2019, 03:48 PM Thread Starter
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No I don't know and I don't have the Blazer here yet ?
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post #4 of 21 Old 03-17-2019, 04:25 PM
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Re: Posi unit for 87 Blazer

If it has the 87 rear it is a 7.5" 26 spline. The easiest and cheapest thing is to find a later 7.6 with factory gov-lock or keep looking until you find an 8.5". Don't waste money on the 7.5" 26 spline.
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post #5 of 21 Old 03-17-2019, 05:02 PM Thread Starter
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So the 7.6 is a direct bolt in? What uses this rear end ?
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post #6 of 21 Old 03-17-2019, 05:44 PM
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Re: Posi unit for 87 Blazer

Any 2wd pickup or blazer, 28 spline was 89 up though there will be varying gear ratios. The code should be in the glove box G80 is the gov-lock. I think we have a sticky with gear ratio codes. Get the whole rear end, I believe 98 up are disc.
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post #7 of 21 Old 03-17-2019, 05:59 PM Thread Starter
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Thanks for the help I will have to check into finding one.
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post #8 of 21 Old 03-17-2019, 06:03 PM Thread Starter
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Oh and I currently drive a 98 S10 2wd and it has drum rear brakes
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post #9 of 21 Old 03-17-2019, 06:52 PM
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Re: Posi unit for 87 Blazer

all S10 trucks are drum brake except the 98+ 4WD
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post #10 of 21 Old 03-17-2019, 07:18 PM
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Re: Posi unit for 87 Blazer

Actually, I wasn't aware the pickups didn't get them, I've only had first gens until I bought a 2003 crew cab. No problem though the 2wd blazer rear end will bolt in, got one in my first gen.
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post #11 of 21 Old 04-03-2019, 07:51 PM Thread Starter
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Ok so I decided after no luck on finding a 3:73 S10 posi I went with the 8.8 Ford so today I went a picked up a 8.8 out of a 91 explorer and was told it's a 3:73 ratio. This is the ring gear picture does anyone know how to decode this?
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post #12 of 21 Old 04-03-2019, 08:02 PM
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Re: Posi unit for 87 Blazer

It should have a tag on the rear with all of the pertinent info. If not...count the teeth and do the math.

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post #13 of 21 Old 04-03-2019, 08:06 PM Thread Starter
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Yes there should of been but there wasn't some where along the way it was removed
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post #14 of 21 Old 04-03-2019, 08:14 PM
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Re: Posi unit for 87 Blazer

take the ring gear teeth divided by the pinion teeth=rear ratio.

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post #15 of 21 Old 04-03-2019, 09:09 PM
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Re: Posi unit for 87 Blazer

Is the 8.8 a limited slip, I thought that was what you were looking for.
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post #16 of 21 Old 04-03-2019, 10:04 PM Thread Starter
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Yes the 8.8 is a Limited slip unit.
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post #17 of 21 Old 04-03-2019, 10:07 PM
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Re: Posi unit for 87 Blazer

Doesn't ford put the number of teeth on the ring gear like most vehicles? Like 41-11 for 3.73?
I suspect the 41? in the pic is part of that. Ford didn't offer a 41-10 (4.10 ratio).
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post #18 of 21 Old 04-04-2019, 08:27 AM Thread Starter
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Well I heard that they did I read that it was the two numbers after the letters and the next two letters. Which would be the 41.
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post #19 of 21 Old 04-04-2019, 11:26 AM
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Re: Posi unit for 87 Blazer

You can divide the ring gear number of teeth by the pinion number of teeth to be sure.
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post #20 of 21 Old 04-04-2019, 11:30 AM
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Re: Posi unit for 87 Blazer

Apparently he doesn't want to do that...post 14.

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post #21 of 21 Old 04-16-2019, 06:18 AM
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Re: Posi unit for 87 Blazer

Passenger side axle tube, facing forward, about 6" inboard of the pumpkin. Use a wire wheel or brush to make it readable. You will get the axle code from what was in it when it left the factory.

82-87 = 7.5 26 spline
88-92= 7.5 26 spline AND 7.6 28 spline
93 on= 7.6 28 spline


Go with a Truetrac if you have the 26 spline axles. If you have the 7.6 with 28 spline axles grab a Zexel Torsen from a 4th gen f body. Direct swap, same as Truetrac, it's a helical gear LSD...

-NEW DAILY. '86 Blazer 54k miles!!!
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