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Turbo 400 With NP208 To NP205 Conversion

B

Bohemian

Guest
82 K5 Blazer that came with a 700-R4 and NP208 now has a Turbo 400 and NP208.
I know the Turbo 400 has the 2-1/2" 32 spline output shaft, because I had to ask the shop doing the tranny r&r for that info so i could order the turbo 400 I want to them to replace the one that shit the bed. (I can't do the tranny r&r by myself because of m/c accident injuries)
Other than that I don't know any other details on my current tranny/transfercase combo.

I want to order a offroad design np205 to replace the np208 with at same time and I want to know if it's plug and play or IF I have to buy any adapters etc.
In addition, The ORD NP205 Page is asking a lot of questions I can't answer.

E.G.:
https://www.offroaddesign.com/remanufactured-gm-np205.html

IF there's already a CK5 Thread that itemizes that recipe info, all or in part for my combo please post the link(s) as I could not find that info thus far, probably my search fu is lacking this am.

Thanks in advance.
 
Short story, you will want the adapter between the th400 and the 205. Second would be the factory shifter. If you don’t have these, those are items you need to locate

All of those other items, the folks at ORD can take care of over the phone. Most likely if you’re using it as a stock application, it will simplify things over how some users are putting them in crawler rigs
 
You will use an np205 with the long input gear.
It fits in the figure 8 and round pattern cases the same.
If I were you, I would find a tall th400 np205 figure 8 adapter and put a long input gear in it. That would keep your crossmember from changing.


If you choose a round pattern case, youll use the short adapter with the W or S Shape crossmember.

Lastly I think the 208 is an excellent tcase and if the case isnt broken, run it.
 
obijuank5 said:
You will use an np205 with the long input gear.
It fits in the figure 8 and round pattern cases the same.
If I were you, I would find a tall th400 np205 figure 8 adapter and put a long input gear in it. That would keep your crossmember from changing.


If you choose a round pattern case, youll use the short adapter with the W or S Shape crossmember.

Lastly I think the 208 is an excellent tcase and if the case isnt broken, run it.
Click to expand...

my np208 is covered in jbweld and leaking, another reason i want to upgrade to the np205 at same time tranny is replaced.
 
Bent77 said:
Short story, you will want the adapter between the th400 and the 205. Second would be the factory shifter. If you don’t have these, those are items you need to locate

All of those other items, the folks at ORD can take care of over the phone. Most likely if you’re using it as a stock application, it will simplify things over how some users are putting them in crawler rigs
Click to expand...

is the np205 shifter different then the np208?

thanks in advance.
 
Any of the CUCV 205’s will have the long input shaft. Round pattern 205 also has the long input. Either of those will work as is with the factory adapter from the 205. Regular figure 8 205 can be used with the long 32 spline input and a factor 400/205 figure 8 adapter.
 
Based on what you all have noted so far & some related research I have some more related questions.

1. Is the GM NP205 Shifter the same for long rail (late np205) and short rail (early np205) and if not are they interchangeable?

2. Will the NP208 to NP205 swap on a Turbo 400 require different drive shafts & yokes? ORD's GM NP205 page gives me lots of options on yokes. I was hoping to not have to get new drive shafts made till I put the 6" lift in.

3. ORD only sells the figure 8 GM NP205 Transfer Case, it's not clear to me at the moment if the turbo 400 to np205 adapter has any bearings in it i need to order separate, i don't see any of those adapters listed with bearings or requiring them but they look like they might.

thanks in advance.
 
Based on what you all have noted so far & some related research I have some more related questions.

1. Is the GM NP205 Shifter the same for long rail (late np205) and short rail (early np205) and if not are they interchangeable?

There are several 205 varieties. Im fairly confident in a shape split at 84 and then for 85-90.
@thatK30guy probably cant confirm.



2. Will the NP208 to NP205 swap on a Turbo 400 require different drive shafts & yokes? ORD's GM NP205 page gives me lots of options on yokes. I was hoping to not have to get new drive shafts made till I put the 6" lift in.

You will require driveshaft changes.

3. ORD only sells the figure 8 GM NP205 Transfer Case, it's not clear to me at the moment if the turbo 400 to np205 adapter has any bearings in it i need to order separate, i don't see any of those adapters listed with bearings or requiring them but they look like they might.


No bearings in the adapters. Round pattern may be a call for availability kind of thing.

thanks in advance.
 
Last edited by a moderator:
Round pattern started in mid 85. CUCV are figure 8 even if they are 85-87.
 
To answer a few questions:
Shifters: the early style (short rail) is typically found on 1960's era np205's. Not super common. You can convert the rails from short to long easy enough. If you end up with a complete working np205 shifter then use that. If you are missing anything significant, look at converting to a twin-stick shifter (ORD, JB fab, NWF, etc... lots of companies make these kits) it will add drivetrain flexibility and make shifting much easier than the factory style

Driveshafts: you will likely need new driveshafts. Cant tell you for sure until you bolt it all up and measure. The front will probably be a very similar length, maybe the old shaft will work, maybe it wont. The rear is probably a slip yoke right now on the 208, and there are both slip yoke and non-slip style 205's. Also the cases are just physically different sizes, so the rear shaft will probably not fit anymore.

Adapter: I dont think either the early or late th400-np205 adapters have a bearing. Its just a cast iron adapter with no moving parts.
Pretty much any np205 can be converted to work behind a th400, just depends on how much work you will have to do to get it there. Once you have a case, you can start looking into solving these issues.

Why are you set on going NP205?
Some drawbacks: 1.96:1 low range is a huge difference from the 2.72:1 that the np208 has. They are HEAVY: 140 pounds vs 75 pounds of a np208.

Most people go NP205 either because they already have one (sounds like you dont) or they know they will need the strength of the NP205.
If there is nothing mechanically wrong with NP208 you can probably tear it down and re-seal the case for cheap. You can probably find a good replacement np208 for half the price of a np205 and not have to deal with shifters/driveshafts mods at all.
 
To reiterate my current NP208 Case is covered in jbweld and is leaking...

It's out anyway right now for the turbo 400 r&r.

Everything I've ever read about GM Transfer Cases says the NP205 is the best & strongest one, seems logical since I gotta do something with the fubar'd transfer case anyway; may as well go all out for a ORD NP205.

From what I've learned from you all so far in this thread, the deciding factor for me is the new drive shaft requirement, that shit ain't cheap and I'll need drive shafts when I put the 1-ton axles and 6" lift in anyway and I'm not able to do the axles and lift right now because I need to rebuild the 14bolt & dana 60 I bought...

And I have not bought the 6" lift kit yet either, which looks like the superlift k422 I want will set me back a grand all in with everything I need...

Making this too much to do in one shot for me money wise and I don't want to have drive shafts made more then once...

So I guess I'm off to find a cheap NP208 without a busted case to get me by till I can do the np205, 1 ton axles, 6" lift and drive shafts at the same time.

When I buy the figure 8 NP205 from ORD is it desirable to get non-slip yokes and non cv yokes?

thanks in advance.
 
It’s generally preferred to have the drive yoke output (re: no slip yoke)
In this scenario, if you break the rear driveshaft, you can unbolt it and go with the front. Yes, I’ve actually needed this

You will very likely want a CV driveshaft for both the front and the rear on a 6”
 
You'll use a figure 8 TH400 to NP205 adapter, either new or used. This is '84 and older TH400/205 stuff. Then we'll build the figure 8 205 with a long input to accommodate the shorter shaft in the TH400. Shifter can be stock or we can do a twin for it. With a 6" lift in a K5 you'll want CVs on the Tcase end of both driveshafts. You'll want to set up the pinion angle in the rear to work with that by shimming or setting perches so the pinion points right at the driveshaft.

Got ya covered?
 
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