V8 400 c. in. common, or even exist in K5's?

[OrngK5]

Here's the confusion - All part identification stickers list my engine size as V8 400 CID Auto, including the metal stamp from the plant that manufactured the vehicle, but repair shops and mechanics list it as a V8 350 auto. I'm baffled, since I was looking into swapping out the NP203 with a NP205, and I was looking for the transmission ID (TH350 or TH400, which I'm now unsure of... ) so I could find a correlating NP205. So my question is, did the K5 ever come with a 400 ci V8? If so, is the transmission going to be a 3-speed TH400 or TH350? I'm embarrassed to say the least, but confused all the same... Thanks for any help!

P.s. It's gasoline, not a diesel.

 

[StevoandaRedK5]

'75-80 K5's could come with the 400ci, and could have come with either the th350 or th400

here's how to identify the trans you have, look at the shape of the pan:

 

[dfl701]

At the home page is the specification link. Should help out alot. They did come with a 400 as an option

 

[ragedracer]

I had a 76 with a 400cu backed by a TH400, IIRC. I had the engine reworked and they were ordered all the wrong parts because they assumed it was a 350.

 

[4X4HIGH]

I owned a 1976 blazer that was a factory 400/TH350/203

 

[OrngK5]

Hey thanks a ton guys! It's a 78' so it's probably a good thing I ran into this earlier and before any major transmission or engine parts needed replacement, again thanks!

 

[OrngK5]

At the home page is the specification link. Should help out alot. They did come with a 400 as an option

Yeah, I checked the specifications link and the 305, 350, and 400 were listed. I just wanted to make quadruple sure that it was indeed a 400CID.

I owned a 1976 blazer that was a factory 400/TH350/203

Thanks, with that said, the TH350 and TH400 were both used and didn't need to match the factory CID? I could be needing to look for a 205 transfer case for a TH400 it sounds like if that's the case.

 

[toomany]

Thanks, with that said, the TH350 and TH400 were both used and didn't need to match the factory CID? I could be needing to look for a 205 transfer case for a TH400 it sounds like if that's the case.

The transmission is an independant option of the motor. But logicly, bigger motors should have gotten the heavier transmission.

All SBC's (and BBC's) have the same bellhousing pattern. Unlike some other manufactures who decide to change things for no apparent reason.

 

[OrngK5]

'75-80 K5's could come with the 400ci, and could have come with either the th350 or th400

here's how to identify the trans you have, look at the shape of the pan:

After looking at this diagram, it looks like it's a 400CID coupled to a TH350 married to a NP203 transfer case. I looked at ORD for a NP205 conversion, and they have modification adapters called the Doubler, any thoughts on this? I won't be wheeling a whole lot, but having a bulletproof transfer case just seems like a wise idea. Since I have the TH350 married to the NP203, it looks like I'll need their GM NP203 to GM 32 spline NP205 adapter plus the shifters for both the 203 and 205. Is the Doubler a solid modification? Or should I keep an eye out for a NP205 for a GM TH350?

 

[dremu]

After looking at this diagram, it looks like it's a 400CID coupled to a TH350 married to a NP203 transfer case. I looked at ORD for a NP205 conversion, and they have modification adapters called the Doubler, any thoughts on this? I won't be wheeling a whole lot, but having a bulletproof transfer case just seems like a wise idea. Since I have the TH350 married to the NP203, it looks like I'll need their GM NP203 to GM 32 spline NP205 adapter plus the shifters for both the 203 and 205. Is the Doubler a solid modification? Or should I keep an eye out for a NP205 for a GM TH350?

The Doubler is intended for hardcore four wheeling, by giving you a second transfer case (1:1 high, 2:1 medium, 4:1 low.) You don't need to do this.

For street and mild off-road use, your stock powertrain with the NP203 will do you just fine.

If you really want crazy bulletproof, then yeah, you could get an NP205 for your TH350. They're fairly rare, IIRC, but out there.

-- A

 

[imiceman44]

After looking at this diagram, it looks like it's a 400CID coupled to a TH350 married to a NP203 transfer case. I looked at ORD for a NP205 conversion, and they have modification adapters called the Doubler, any thoughts on this? I won't be wheeling a whole lot, but having a bulletproof transfer case just seems like a wise idea. Since I have the TH350 married to the NP203, it looks like I'll need their GM NP203 to GM 32 spline NP205 adapter plus the shifters for both the 203 and 205. Is the Doubler a solid modification? Or should I keep an eye out for a NP205 for a GM TH350?

Where in CA are you?
If you want to make your 203 better, you could put a part time kit in it.
Or I have a 205 that will bolt to your th350.
If you are interested let me know, I am in northern CA sacramento area.

 

[OrngK5]

Where in CA are you?
If you want to make your 203 better, you could put a part time kit in it.
Or I have a 205 that will bolt to your th350.
If you are interested let me know, I am in northern CA sacramento area.

It has the part time adapter for the 203 already installed, as for the 205, is it 27 or 32 spline? I assume 27 spline, and possibly a fixed rear output yoke? By the way thanks for the offer too, I live in northern CA about 30 mins or so out of Sacramento, Roseville, Granite Bay, Folsom area if you're familiar with that.

 

[OrngK5]

Also, just confirmed with the casting number on the block, 400cid 74-80 2bolt main

 

[79rustyk10]

I have seen quite a few blazers with the 400 sbc but havent seen one that didnt have a Th350/203. is the TH 400 really rare in 1/2 tons and blazers? Ive never seen one that wasnt in a 3/4 ton.

 

[imiceman44]

It has the part time adapter for the 203 already installed, as for the 205, is it 27 or 32 spline? I assume 27 spline, and possibly a fixed rear output yoke? By the way thanks for the offer too, I live in northern CA about 30 mins or so out of Sacramento, Roseville, Granite Bay, Folsom area if you're familiar with that.

Very familiar with that area.
Lived in Rancho cordova and had family in that area, now I live in Lincoln, CA, so I am about 30 minutes from you.
Yeah the 205 I have is 27 spline complete with adapter and sleeve.
Let me know if you want it.
I have to check on the rear output, I think it is slip yoke, but those can easily be changed from any donor 205.

 

[imiceman44]

I have seen quite a few blazers with the 400 sbc but havent seen one that didnt have a Th350/203. is the TH 400 really rare in 1/2 tons and blazers? Ive never seen one that wasnt in a 3/4 ton.

Well I remember the 76-77 years the th400 was standard on 400 ci engine options.
It was opionnal with the 350 ci engine.
I don't know other years, only these 2 because I had the brochures.

 

[OrngK5]

Very familiar with that area.
Lived in Rancho cordova and had family in that area, now I live in Lincoln, CA, so I am about 30 minutes from you.
Yeah the 205 I have is 27 spline complete with adapter and sleeve.
Let me know if you want it.
I have to check on the rear output, I think it is slip yoke, but those can easily be changed from any donor 205.

Right on I know where Lincoln is, how much are you asking?

 

[imiceman44]

Right on I know where Lincoln is, how much are you asking?

I want $250
And I will meet you or deliver if I happen to be going that way, I might be soon.
They are getting rare and I paid more than I wanted when I got it, but now I am keeping the 203 in mine and selling the truck as is, and trying to get some of my money back with this one.

 

[OrngK5]

I want $250
And I will meet you or deliver if I happen to be going that way, I might be soon.
They are getting rare and I paid more than I wanted when I got it, but now I am keeping the 203 in mine and selling the truck as is, and trying to get some of my money back with this one.

Right on, I don't mind driving to pick it up. My K5 is pretty much stock, the reason I was looking into getting the NP205 was based on a recommendation by the shop I plan on having install the lift kit at. The mechanic said for the mild wheeling I'd do, I could be fine with the NP203, but there is a chance later on it could blow up. I don't plan on rock crawling or bogging at all, but I'd just hate for the transfer case break when I may need it most...

In your opinion, should I compromise the overall value by strengthening the system? Or leave the 203 on there, keeping it stock, and just take it easy?

 

[imiceman44]

Right on, I don't mind driving to pick it up. My K5 is pretty much stock, the reason I was looking into getting the NP205 was based on a recommendation by the shop I plan on having install the lift kit at. The mechanic said for the mild wheeling I'd do, I could be fine with the NP203, but there is a chance later on it could blow up. I don't plan on rock crawling or bogging at all, but I'd just hate for the transfer case break when I may need it most...

In your opinion, should I compromise the overall value by strengthening the system? Or leave the 203 on there, keeping it stock, and just take it easy?

I had a blazer stock with a 203 before I used it as a daily driver, and one day the chain broke, wedged up between the gear and the case and BOOM, it exploded the case.
I went and got a 205 and put it in and wheeled it and drove it to work for 6 years, no problems ever.
I ended up parting it after the 6 years.
Now I have a chalet and it has the 203 and I was going to change it but now I just want to sell it.
As for compromising the value of your truck, the 205 doesn't change that, it actually adds to the value.