Author Topic: how do i manage to make this work..............  (Read 1748 times)

Offline rusty_but_trusty_86

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how do i manage to make this work..............
« on: June 21, 2014, 06:45:04 PM »
alright y'all, i have a 1987 chevy v10(pretty much k10 but gm slapped a v instead of a k since it was fuel injection) long story short, trans in it is shot and the core is bad also with cracks, so thats pretty much out the window because im not about to screw with a cracked bellhousing. anyways, the truck was special ordered in 1987 with the turbo 400 instead of the 700r4.. they somehow made it work with the np208... well i have a trans and a transfer case for the truck.... heres the thing, it is a turbo 400 hd 2 wheel drive trans, and an extra np208 tranfer case.......... how in the world can i make this work, let alone making it bolt up nice with the 208......?
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Offline zieg85

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Re: how do i manage to make this work..............
« Reply #1 on: June 21, 2014, 07:16:44 PM »
Can't answer your question however the V-10 explanation was due to the new body style introduced in the 1988 which were the C/K then.  Our Crew cabs and Suburbans continued to be R/V through 1991
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline HAULIN IT

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Re: how do i manage to make this work..............
« Reply #2 on: June 21, 2014, 09:06:17 PM »
If the truck has a turbo 400 hooked up to a 208 now...all you need to do is take the output shaft out of the bad trans & put it in the 2wd drive case, thus making it the same as what was in there already. Then you will be able to use the same transfer case you already are using. If the shaft swap is out of your range of ability, find a local trans. shop...this should be a routine deal to them. Lorne

Offline rusty_but_trusty_86

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Re: how do i manage to make this work..............
« Reply #3 on: June 21, 2014, 09:16:30 PM »
the output shafts will swap and mesh right?
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Offline Irish_Alley

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Re: how do i manage to make this work..............
« Reply #4 on: June 21, 2014, 10:50:01 PM »
no, you have to take the trans apart to remove the shaft. its the last thing that comes out. but what style output shaft on the 2wd th400 do you have? is it a slipe toke or bolt on yoke?
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Offline Irish_Alley

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Re: how do i manage to make this work..............
« Reply #5 on: June 21, 2014, 11:14:21 PM »
dont know for sure but i know on the th350 and 4l80e you can cut the splines down to make it work as a 4wd trans but they have to be the right style splines and the shaft should be splines all the way down. so when you cut it down you will still have the right amount of splines showing. or you could buy a spacer and put it on
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Offline Irish_Alley

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Re: how do i manage to make this work..............
« Reply #6 on: June 21, 2014, 11:22:53 PM »
Found this


now apparently the 2wds are for the most part  9.25" the 4wd are like this
first one (1.25") is for the 203
the next (2.5") is the 208
and the 3rd (9.25") is the 205
EDIT: acording to another sorce the 205 and 2wd are the same. not 208 and 2wd
« Last Edit: June 22, 2014, 12:08:54 AM by Irish_Alley »
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Offline pholliday1

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Re: how do i manage to make this work..............
« Reply #7 on: June 23, 2014, 12:08:37 PM »
Actually have done this before, as stated above swap tail shafts and remove end housing on 2wd trans very simple. Turbo 400 to np208 is a great setup I'm currently running it in my 90 v3500. Side note the "majority' of military square bodies run 400 to 208 set up. The exception being trucks that have a pto setup they use a 205 case.
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Offline rusty_but_trusty_86

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Re: how do i manage to make this work..............
« Reply #8 on: June 24, 2014, 08:05:14 PM »
so i just gotta swap tail shafts? possibly a dumb question, but how hard would it be for me to do it instead of taking it to a shop? I am great at tearing down and rebuilding sbc 350s, me and a group of buddies were on a competive team and did complete ear downs and assemblies in right around 22 minutes. ive heard from a few people that turbo 400s are some of the easiest automatic trans to do... how true is this?
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Offline thefarmboy21

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Re: how do i manage to make this work..............
« Reply #9 on: June 25, 2014, 02:11:23 PM »
I've never tried it but ice always been told you have physically tear te trans apart and change the output shaft to make it work. But I dont know for sure. But as far as the main case and internals it's all the same. At the most you should only have to tear apart and change the shaft (and whatever else is bad)
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Offline pholliday1

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Re: how do i manage to make this work..............
« Reply #10 on: June 26, 2014, 11:40:19 AM »
Just do a little research and document as you go its not difficult. There is a retainer bolt that comes up from the valve body that holds on of the drums in place but other than that its fairly simple.
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1991 V3500 CREWCAB SRW 454TBI GMC
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1989 v3500 crewcab 454TBI 5" lift