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Old 10-04-2017, 10:31 PM   #1
70K10Hunter
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NP 203 to NP205

K so I've been scouring the threads on this and it appears to be straight forward just want to double check my info.....I have a 77 GMC 3/4 4x4 it currently has a 203 bolted to a TH350 I am getting a 205 that was bolted to a th350. Can I use my existing transfer case cross member? I'm assuming that I will have to move it back a bit. What about drive shafts?
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Old 10-05-2017, 06:27 PM   #2
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Re: NP 203 to NP205

Cross member will work front driveshaft needs to be shorter and rear longer.
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Old 10-05-2017, 10:04 PM   #3
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Re: NP 203 to NP205

also make sure you get shifter parts . and adapters are t-case specific as with trans .

dont forget the female to female coupler sleeve for the 205 .
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Old 10-05-2017, 11:02 PM   #4
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Re: NP 203 to NP205

Make a doubler out of the 203 range box...
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Old 10-06-2017, 07:02 PM   #5
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Re: NP 203 to NP205

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Originally Posted by sweetk30 View Post
also make sure you get shifter parts . and adapters are t-case specific as with trans .

dont forget the female to female coupler sleeve for the 205 .

I am getting the shifter, trans output coupler/adapter, and box.
the box I'm getting was already coupled to a TH350.
So I think I'm good.
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Old 10-07-2017, 10:59 AM   #6
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Re: NP 203 to NP205

is it evengoing to bolt up? the adapter for the np203 is like a 1/4 inch thick where as the 205 is a few inches thick the transmission output shaft is going to be way to short

i wanted to run a np208 after i threw out my np203. i just brought the trans to a shop and had a longer output shaft installed
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Old 10-07-2017, 11:08 AM   #7
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Re: NP 203 to NP205

I guess I will find out when it gets here. If it is too short I will get a different one and install it when I rebuild the tranny.
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Old 10-07-2017, 05:25 PM   #8
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Re: NP 203 to NP205

th350 with 203 or 205 use same output shaft length in trans .

the 208 and 241 used another length .
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Old 10-10-2017, 11:59 PM   #9
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Re: NP 203 to NP205

it will bolt right up, you will need to move your crossmember and redrill holes in the frame if i remember right, I did this same conversion 30 years ago.
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Old 10-11-2017, 06:32 PM   #10
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Re: NP 203 to NP205

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it will bolt right up, you will need to move your crossmember and redrill holes in the frame if i remember right, I did this same conversion 30 years ago.

Yes fully figured on that, my frame on my 77 like my 70K10 has 2 brackets just aft of the existing cross member on each side with a bolt already in one hole. I think that is where the CM will go. We'll see.
That actually got me thinking I wonder if a drive shaft out of a early 70, 71, 72 K10 or 20 would work???
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Old 10-14-2017, 11:19 AM   #11
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Re: NP 203 to NP205

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Originally Posted by sweetk30 View Post
th350 with 203 or 205 use same output shaft length in trans .

the 208 and 241 used another length .
interesting. like i said in the previous post my np203 adapter is like 3/4 inch thick the adapter i have attached to a np205 is like 4 inches thick, but its for a th400transmission

i just remember trying to put a np208 onto a th350 and that out put shaft was no where near long enough, just had a trans shop put one in.

didnt know it was a different situation with the 205s and th350. learn something new everyday
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Old 10-14-2017, 02:17 PM   #12
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Re: NP 203 to NP205

yes th305 203/205 same output on trans .

th400 203 is short output on trans .

th400 205 is 2 diffrent output shafts for the fig8 style short input 205 or the round 6 long input 205 .
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Old 10-19-2017, 10:10 PM   #13
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Re: NP 203 to NP205

got my Tcase the other day I will check for fit this weekend after I pull the cab.
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Old 10-22-2017, 12:09 AM   #14
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Re: NP 203 to NP205

So I pulled my cab today and then pulled the 203. The 205 bolted right up to my tranny no mods needed. Before I pulled anything I marked the location of the front of the trans with a straight edge then mounted everything, used same mounts and did not need to move the cross member. Its all good, now just need to do the drive shafts.
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Old 10-22-2017, 12:23 PM   #15
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Re: NP 203 to NP205

what's the length difference between the 203 and now the 205?
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Old 10-22-2017, 03:07 PM   #16
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Re: NP 203 to NP205

the 203 is 22 1/4" and the 205 is 16" from mounting face to trans and to center on rear yoke.
so 6 1/4".
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