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Hi Guys

I need your help. I have 2000 sonoma extended cab 4.3 w/7.5 3.42 rear end. I picked up a 8.5" posi 3.42 with disc brakes out of a 2002 Xtreme blazer 5 sp. I was told this is a easy swap. The problem I have is that the extended cab trucks have a two piece driveshaft and the rearend has a flange the driveshaft bolts to. The rearend from the blazer has a yoke that the u-joints bolts up to. My question is can the flange my truck (7.5") be swapped onto the new (8.5") rearend??? Are the pinion shafts the same size, same spline?? Are there part(s) I could buy to make this work?? Any ideas what I can do????????

Thanks
RKR
 

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the youngest has been
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pictures would help, icant pictuer waht your saying
 

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No the Universals are different and so is the distance fromt he tranny to rear end. I don't know what to tell ya on how to fix the problem but I can promise you theyare different.
 

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Blown ex ***
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i have yet to do this mod. but i would say (correct me if im wrong) that the driveshaft wil have to be shortened. if thats the case, just have them put the correct end and joint on it.
 

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Getting faster
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Why are you doing the swap? Looking to beef up the rear end? IMO, Id get rid of the 2 peice and go with a 1 peice driveshaft if you can.


Oh and Tipp, I think theres a pic in the JTR swap book. I can't find mine right now, but I though there was.

In most cases, when swapping from 7 or 8.5", the driveshaft needs shortened becasue the differential is larger.

Here a pic to show you. Obviously the shorter one is the 7.5". Both are standing up on the pinion shaft. Since the 8.5" uses the same axle tubes as the 7.5", its gonna mount the same as the 7.5" does. So, thats how much more the pinions gonna be sticking out.

 

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Static> Bags
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You will need a new driveshaft. (i think)

It will need to be like a 1 1/2 shorter or really close to that.
 

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Gaaoooooo
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Don't the automatic extended cab trucks also use a double cardan u joint which would possibly account for differences?
 

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ZR2 Interceptor
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What is the benefit to swapping out these rears? I hope its not just for the Gov-Lok?!? A carrier swap would be significantly easier than all this nonsense.
 

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Gaaoooooo
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ppap said:
What is the benefit to swapping out these rears? I hope its not just for the Gov-Lok?!? A carrier swap would be significantly easier than all this nonsense.
Well if he got a good deal on the rearend, even if it cost him $500, I'd still say this swap is worth it for the added strength as well as the rear disc setup.
 

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FWD's suck
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ppap said:
What is the benefit to swapping out these rears? I hope its not just for the Gov-Lok?!? A carrier swap would be significantly easier than all this nonsense.
the 8.5 is alot stronger then the 7.5. WIth the 8.5 you can run slicks and good amount of HP and not have to worry about it. Ive seen guys go 10's with the 8.5. Anything over a few 300 HP with a 7.5 and your gonna break it. Put slicks on it and your on borrowed time also.
 

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zerogravity58 said:
the 8.5 is alot stronger then the 7.5. WIth the 8.5 you can run slicks and good amount of HP and not have to worry about it. Ive seen guys go 10's with the 8.5. Anything over a few 300 HP with a 7.5 and your gonna break it. Put slicks on it and your on borrowed time also.

How many street driven 300 hp s10 you see lately..... ????? Camaros and firebirds had the same 7.5 10 bolt and they had 320 hp stock . IF you are at the track with a v8 go for it, if not beef up the 7.5 with a girdle and forget it.
 

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.. lets see he has drum brakes and no posi :cool: yeah i would want to bolt in a disc brake posi rear end thats stronger too

i know on the 7.625 you just change the yoke and seal on the trans i would think the same thing applies on the 8.5 as the yokes look the same so change the yoke off you stock rear and you will need to change the seal as i have done this before and the seal is different... thier is no need to change the drive shaft
 

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edit sort of on my last post is says change the yoke and seal on the trans it should say change the yoke and seal on the rear end
 

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Jetmeck said:
How many street driven 300 hp s10 you see lately..... ????? Camaros and firebirds had the same 7.5 10 bolt and they had 320 hp stock . IF you are at the track with a v8 go for it, if not beef up the 7.5 with a girdle and forget it.
how many? i drive mine on the street and ive also broken 2 7.5's..obviously you dont know many camaro or firebird people that dragrace because they break the 7.5's all the time with slicks! Thats why so many people change to a 9 in or 12 bolt because the 7.5's dont hold up. They can be built stronger but the MAX you will get out of it is not much over 300HP without slicks.
 

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zerogravity58 said:
how many? i drive mine on the street and ive also broken 2 7.5's..obviously you dont know many camaro or firebird people that dragrace because they break the 7.5's all the time with slicks! Thats why so many people change to a 9 in or 12 bolt because the 7.5's dont hold up. They can be built stronger but the MAX you will get out of it is not much over 300HP without slicks.
HEH, Knothead....
Only way you are breaking 7.5 10 bolts with a s-10 is with slicks and a v-8 and a serious clutch dump and if you care to reread my post "if you are going to the track or have a v-8, go for it" meaning put in the 8.5 10 bolt. Go to thirdgen.org , many firebirds and camaros 7.5 10 bolts live long with up to 400 hp on street tires. Again just for you going to the track with slicks, then yes upgrade.
 

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According to the JTR book (Chevrolet S-10 Truck V8 Conversion Manual), page 12-11, the flange from a 1970's Caprice, GM part #3996118, will bolt on to the 8-1/2" rear end, and work with your existing driveshaft.
 
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