Author Topic: NP205 or NP208  (Read 27763 times)

Offline gcochran223

  • Registered Users
  • *
  • Posts: 148
NP205 or NP208
« on: March 18, 2012, 02:54:34 PM »
i am buying a 85 seirra with a np208 and it needs a motor and tranny.i have a 355 and th400 and np205 from another truck. what are some of the pro's and cons of me wanting to swap out that 208 for the 205 i currently have.the only reason im wondering is its one less thing to remove from the ground on a creeper and if there virtually the same. any info appreciated
1986 k15, 355, th400 ,np205, Corporate 10 bolt,corporate 12 bolt, 8" suspension lift.4.56 yukon gears.

Offline Jason S

  • Senior Member
  • ****
  • Posts: 1561
Re: NP205 or NP208
« Reply #1 on: March 18, 2012, 06:54:58 PM »
While they are both part time transfer cases that were mated behind GM transmissions, they're quite different in every other respect.

The NP205 is generally regarded as the best factory transfer case available for light-duty trucks.  However, the NP208 is not a bad transfer case. Chevrolet put them in the U.S. Army CUCV 1 1/4 ton 4x4 trucks behind a Diesel and TH400 transmission.

If you don't want to have to swap them later, then put in the NP205.  You're probably going to have to modify driveshafts lengths and even mounting type (i.e., slip yoke vs. bolt on yoke).
1973 GMC K2500, Super Custom, Camper Special, 350, TH350, NP203, 4.10's
1974 Chevrolet K10, Custom Deluxe, 350, SM465, NP203, 3.73's

"1) Peace through strength; 2) Trust but verify; 3) Beware of evil in the modern world"

Offline Cody1018

  • Registered Users
  • *
  • Posts: 144
Re: NP205 or NP208
« Reply #2 on: March 18, 2012, 07:03:17 PM »
Like jason said, the NP205 is regarded as the better of the 3 that gm used on these trucks. Some advantages of the 205 is that its gear driven and has a cast iron case, which also means its heavier. The 208 is chain driven, has an aluminum case and also has a lower low gear range than the 205.
1986 Chevy K10 Silverado

Offline Blazin

  • Blazin new trails!
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6130
Re: NP205 or NP208
« Reply #3 on: March 18, 2012, 09:48:53 PM »
What was the transmission in the truck before. If it was an automatic I( am going to assume it was 700R4. If thats the case it won't work with your TH400 as the output shaft splines are not the same. If it was an SM465 then the TH400 will work on it. You also have the transmission to transfer case adaptor to deal with. You would need to get one to mate the 208 to the TH400.
I would stick with the 205. Very rugged, tried and true transfer case.
Some people are like Slinkies. Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs

Offline gcochran223

  • Registered Users
  • *
  • Posts: 148
Re: NP205 or NP208
« Reply #4 on: March 19, 2012, 01:05:43 AM »
the truck im buying the guy who doesnt know much about his sierra on 37s! said it comes with a rebuilt th350 and 208 which are still in. i recently had my th400 rebuilt and it has a 205 bolted to it, the last two being in my 78 k10.i dont trust anyone when buying a car saying things are rebuilt so i wanted to swap in my th400 cause i know its beefed and has less than 1000 miles on it. the truck has half ton axles and im really hoping it doesnt have the 3.08s.
1986 k15, 355, th400 ,np205, Corporate 10 bolt,corporate 12 bolt, 8" suspension lift.4.56 yukon gears.

Offline Irish_Alley

  • Tim
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13319
  • Family is not an important thing. It's everything.
Re: NP205 or NP208
« Reply #5 on: March 19, 2012, 02:55:11 AM »
i would run it till something happens. i would also put the 205 in if i had the option, and if something on the 208 broke. since if the 205 would require new drive shafts its just not cost effective to just swap them out just cause you have the parts.
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Engineer

  • Senior Member
  • ****
  • Posts: 1402
Re: NP205 or NP208
« Reply #6 on: March 19, 2012, 08:44:21 PM »
The 205 setup, no doubt about it. :)
2002 Chevy 2500HD 4x4 8.1/ZF6sp RC/LB
2001 Chevy 2500HD 4x4 6.0/4L85E EC/SB
1997 Chevy Blazer 4x4
1994 Chevy K-2500 4x4 C6P 5.7/4L80E
1979 Chevy K-30 4x4 4sp 4.10
1977 Chevy K-30 4x4 4sp 4.10 454

Dad of an Eagle Scout, and a Life Scout