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#1 |
Registered User
Join Date: Jan 2010
Location: Richmond, MO
Posts: 23
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Tranny Questions
I have a 87 4x4 3/4 ton with the tranny going. It currently has a 400 tranny my question is whether or not I can put a 350 Turbo in it, short shaft or long shaft, and if so what will I have to change. Oh and it has a small block 350 in it.
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#2 |
Robert Olson Transport
![]() Join Date: Oct 2002
Location: recent transplant to NC USA
Posts: 20,287
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Re: Tranny Questions
a 350 will bolt right up but its not as strong a trans. You want a long tail and the driveshaft will prolly need to be either lengthened . Im not sure if you will need the yoke from the th400 or not and you will have a couple of other differences that are n ot hard to change over. In all honesty id just rebuild the th400
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Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!! |
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#3 |
Next project: 1970 K10
Join Date: Feb 2004
Location: Fort Collins, Colo 80524
Posts: 6,685
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Re: Tranny Questions
Don't get mixed up with any tranny that......... oh wait, you mean transmission?
Well then, ![]() But I'm with Bob, keep a TH400 in there. No point in going with a weaker one. Why the desire to go to a 350?
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Bob 1970 Chevy K10 LWB "Goldie" 350/TH350 next project!! 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE Last edited by glock35ipsc; 01-27-2010 at 01:08 AM. |
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#4 |
Registered User
Join Date: Jan 2010
Location: Kitchener, Ontario, Canada
Posts: 94
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Re: Tranny Questions
im pretty sure the case will be the same. A 4x4 trans is different from a 2wd.
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#5 |
Registered User
Join Date: Jan 2010
Location: Richmond, MO
Posts: 23
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Re: Tranny Questions
Well the reason is I can find a 350 easier and that extra gear... I need to lower my rpms at high speeds cuz I am getting blow by at about 60mph and up and I don't really have the money to rebuild both motor and tranny right now and since its just a work/farm truck I didn't think the weaker tranny would be that huge of a difference.... but idk I'm not a transmission guy haha
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#6 | |
Registered User
Join Date: Dec 2007
Location: Palmer, Alaska
Posts: 13,821
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Re: Tranny Questions
Quote:
you can get a 350 with a lock up converter, but it will only drop around 200RPM, and technically it isn't another gear. If you want a 4 speed you will need a 700R4, 4L60E, or 4L80E the latter 2 will need a computer to operate.
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#7 |
Registered User
Join Date: Jul 2007
Location: Sims, NC
Posts: 531
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Re: Tranny Questions
The turbo 400 has a 32 spline output and the turbo 350 and 700r4 have 27 spline output. Neither a turbo 350 nor 700r4 will bolt up in place of the turbo 400. If you want overdrive you will need to find a complete 700r4 with the NP208 transfer case. If you buy the complete unit it will bolt up. Your current transfer case is a NP208. Your drive shafts will have to be lengthened/shortened as the 700r4/208 combo is longer than the 400/208. GM transmission/transfer case swaps are never as straight forward as they should be.
Let me know if you have any questions. Mike Last edited by Mr.Chevy4x4; 01-28-2010 at 09:44 PM. |
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#8 |
Registered User
Join Date: Jan 2010
Location: Richmond, MO
Posts: 23
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Re: Tranny Questions
Well then my next question (might be a stupid one) is can a 2 wheel drive 700r4 have a transfer case mounted to it, I heard 2 wheel drive transmissions cant be made 4, but I have an extra 700r4 sitting around
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#9 | |
Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: Tranny Questions
Quote:
4WD 700R4s has a diffferent output shaft than a 2WD 700R4. The transmission will have to be torn down to install the 4WD shaft. In my opinion a 700R4 is a poor choice for a 3/4 ton truck if you tow or do offroading with it. |
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#10 |
Registered User
Join Date: Jul 2007
Location: Sims, NC
Posts: 531
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Re: Tranny Questions
Yes it can be made to work in your 4x4, but may not be worth the hassle. The output shaft in the transmission would have to be changed. The 2wd and 4wd transmissions had different output shafts. You will also need a 700r4/NP208 transfer case adapter, and a 27 spline input NP208 transfer case. Your transfer case has a 32 spline input.
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#11 |
Registered User
Join Date: Jan 2010
Location: Richmond, MO
Posts: 23
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Re: Tranny Questions
Well that answers all my questions! Well ones I have for now anyways haha thanks everybody its been very helpfull
Last edited by REW_388; 01-29-2010 at 03:09 PM. |
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