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Old 02-25-2007, 02:54 AM
Chris Barry's Avatar
Chris Barry Chris Barry is offline
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Muncie SM465, GM 10 bolt 8.5, GM 14 bolt 10.5 and NP 208 swap

Got a 82 Chevy truck that has a 350 with the muncie SM465(4 speed manual with low), NP 208(pass drop), gm 10 bolt 8.5" front axle and gm 14 bolt 10.5" rear axle(unfortunately semi-floating). Not sure of the gear ratio yet, but that can be changed. I am wondering if the np 208 will bolt to my 727 without any problems so I can swap the axles into my 85 Grand Waggy. Then I can have a NP 208 and 3/4 ton axles.(I can always swap a full floating axle in later)

Any and all input would be appreciated. If I can just swap the parts without any MAJOR modifications(I expect some fabrication to be needed), then my axles will go under my buddies Jeepster. Also wondering if it would be easiest to swap the whole drive train(I like my 360, though).

Well....let me have it
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'85 Grand Waggy 360/727/NP229 33X12.5R15 2inch susp lift with 2inch body lift.(wife's DD)
'86 Grand Waggy all stock with custom sagging springs
'85 Baby Cherokee 2.5L(my new DD)
'89 Chevy K2500 flatbed
'87 Ford Ranger
'84 Renault LeCar
'84 Honda Passport
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  #2  
Old 02-25-2007, 03:28 AM
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wickedwagon767 wickedwagon767 is offline
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For one, the 10.5" 14-bolt is a full-floater. If its a semi-float 3/4 ton then you have a 9.5" ring gear,33-spline c-clip 14 bolt. Still plenty strong for most uses. The full-floaters are easy to differentiate from the semi-float. The full-floaters have massive hubs that stick out several inches from the wheel mounting surface and the differential housing is noticably larger, and hangs down quite low, to a point. Where the 9.5" semi-float differential housing is more egg-shaped.

I believe the SM465 had a 10-spline male output shaft which would suggest that the GM NP208 would have a 10-spline female input. Your TF727 has a 23-spline male output shaft. Furthermore , the GM version of the NP208 that came behind an automatic trans (TH350,700R4 or TH400) had 27-spline female input shafts, which wouldn't work either.

I'm sure you can swap the 23-spline input shaft out of your origional Jeep 208 case into the GM case. Others might chime in on that in more detail soon. I do know that the GM 208's all had the long slip-yoke rear output and no aftermarket fixed yoke is available , if needed( which really isn't necessary if the truck is only lifted a few inches). But, I have seen it mentioned that the back-half of the Jeep NP208 with the factory fixed yoke will bolt on to the GM front half.

You're either going to be swapping the output shaft in the tranny or the input shaft in the T-case, at least, to make this work.

As far as swapping the whole drivetrain....Advance makes decent motor mounts and headers for the small block chevy swap, which of course, is the easiest swap compared to others. Bolt-in GM v-8 conversion radiators are easy to find and while you won't have to worry about input/output shafts if you retain the whole GM drivetrain you're more than likely going to spend more time and money on the complete drivetrain swap than you would by just dissasembling the T-case that you're already pulling out of the Chevy anyway to do an input shaft swap.

If you're still in school and looking for a simple effective upgrade on a budget I'd keep the good 'ol beefy 360/727 combo, swap the input shaft in the GM 208, use the back half of the Jeep case on the Chevy case....do minimal fabwork (if any at all) to the factory crossmember........then all you have to worry about is the fairly simple axle swap and driveshaft mods.

Last edited by wickedwagon767 : 02-25-2007 at 03:39 AM.
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Old 02-25-2007, 04:18 AM
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you shouldn't be sad it's a semi-floating rear....

Al
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Old 02-25-2007, 04:40 AM
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Crazy_Jeepman Crazy_Jeepman is offline
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If you have the NP208 in a 82 Chevy.............I highly doubt the Trans is an SM465, unless it is swapped in. GM 208 never had a Male 10 spline input. It was not mated to an SM465 till about 85 I think, when the SM465 went to the 32 spline output.

As far as swapping the GM 208 in, forget it, it will be way to much work. Input shaft and Clocking issues will just be endless. best bet..........find a Dodge NP208, or Dodge NP205, (will also eliminate the GM slip yoke) that will be a near bolt in deal, possibly some minor grinding to get the T-Case to fully mount with the Jeep Trans Adaptor.
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Old 02-25-2007, 06:57 PM
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Chris Barry Chris Barry is offline
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What I really want is the rear axle. Can I swap components from the 10 bolt to my D44 to make it an eight lug bolt pattern? Or is it only F*rd front axles components that fit?(or am I wrong here, too) I want the rear axle, but don't want to have two different bolt patterns. I also would prefer not changing which side the front diff is on.

I also don't wanna buy some overpriced adapter.
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'85 Grand Waggy 360/727/NP229 33X12.5R15 2inch susp lift with 2inch body lift.(wife's DD)
'86 Grand Waggy all stock with custom sagging springs
'85 Baby Cherokee 2.5L(my new DD)
'89 Chevy K2500 flatbed
'87 Ford Ranger
'84 Renault LeCar
'84 Honda Passport
'66 Yamaha MG-1T
http://www.jpricefamily.org/joy/Chris-Cars.htm

Last edited by Chris Barry : 02-25-2007 at 06:59 PM.
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Old 02-25-2007, 08:01 PM
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Crazy_Jeepman Crazy_Jeepman is offline
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All you need off the 10 bolt is the, Hubs, Rotors, Caliper Bracket, possibly the spindles, if you have the small spindles on your rig. If you don;t have the large spindles on your rig you would want to take them too then. I would grab the axles shafts only because the outers will be good spares for your rig, the inners are wrong.
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  #7  
Old 02-26-2007, 12:39 AM
Chris Barry's Avatar
Chris Barry Chris Barry is offline
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Awesome. That works well then.
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'85 Grand Waggy 360/727/NP229 33X12.5R15 2inch susp lift with 2inch body lift.(wife's DD)
'86 Grand Waggy all stock with custom sagging springs
'85 Baby Cherokee 2.5L(my new DD)
'89 Chevy K2500 flatbed
'87 Ford Ranger
'84 Renault LeCar
'84 Honda Passport
'66 Yamaha MG-1T
http://www.jpricefamily.org/joy/Chris-Cars.htm
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  #8  
Old 02-26-2007, 01:22 AM
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wickedwagon767 wickedwagon767 is offline
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thanks for clearing that up Crazy J

what about the WMS-WMS on the 14-bolt when compared to the factory front D44 on CB's '85?

You'll have a wide full-width axle out back and a narrow track front
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  #9  
Old 02-26-2007, 02:15 AM
Chris Barry's Avatar
Chris Barry Chris Barry is offline
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Quote:
Originally Posted by wickedwagon767
thanks for clearing that up Crazy J

what about the WMS-WMS on the 14-bolt when compared to the factory front D44 on CB's '85?

You'll have a wide full-width axle out back and a narrow track front

I could live with that for a little while till I get a D60 for the front.
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'85 Grand Waggy 360/727/NP229 33X12.5R15 2inch susp lift with 2inch body lift.(wife's DD)
'86 Grand Waggy all stock with custom sagging springs
'85 Baby Cherokee 2.5L(my new DD)
'89 Chevy K2500 flatbed
'87 Ford Ranger
'84 Renault LeCar
'84 Honda Passport
'66 Yamaha MG-1T
http://www.jpricefamily.org/joy/Chris-Cars.htm
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  #10  
Old 02-26-2007, 03:25 PM
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