NP205 in 76? K20 - what do I need? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crosby · 03-10-2005, 11:16 AM

I am trying to put a NP205 in my mid 70s 3/4 ton 4x4. It has an 87 body and bed, but the frame is rotted in front of the rear spring mounts. So I bought another frame, and plan on putting the drivetrain in before I pull the body over. I have the original? Th400 and NP203 in it (full time ) and want to put a NP205 I picked up for it when I got the frame. I have discovered the transfer case adapter I need is expensive, and don't know what else I need. Isn't there a coupler in there too? I am not concerned about driveshafts or speedo cables yet, but what do I need to make the 205 work? Thanks very much for any help you guys can provide.

77gmcjoe · 03-10-2005, 07:52 PM

I've just put a 400/205 into my truck, so maybe I can help.
I had a 400/203 combo I was going to use, but ended up finding a rebuilt 205. After finding a 400/205 adapter (got lucky there), I discovered the tailshaft of the tranny I had wasn't long enough to mate with the 205 tcase. The adapter between my 400/203 was about an inch thick, where the 400/205 adapter was about 6 inches thick. BTW, the tailshaft of a correct 400TH goes directly into the 205 tcase, no coupler needed. You do have to have a 205 that has the correct input, there were several different styles. Again, luckily, I was able to get the correct 400TH with the longer tailshaft to mate with the 205. You'll need a 205 shifter as well, it's totally different than the 203 version.
I know you said you weren't worried about driveshafts yet, but I'll tell you that mine are being modified right now (rear lengthened, front shortened). Can't wait to get them back so I can finally test drive it!

All in all, it was quite a PITA, but I'm hoping in the end it will be worth it.

Joe

1969 GMC · 03-10-2005, 08:27 PM

good luck finding the correct version. Depending on what kind of adapter you find for it (early figure 8 or later 6 bolt circle), you will need either a long (fig 8) or short (circle/6) 32 spline female input gear 205, as well as the shaft for the tranny like Joe mentioned.
both of these were only found in K30's.

another solution is to find another kind of 205 case (10 or 27 spline) and have the bearing hole machined for the 32 spline gear (which are larger than 10 or 27), then buy a 32 spl gear (~$150) and put it in. then, you need the correct adapter...so it would be easier to just find a 400/205 combo, iow.
good luck!

crosby · 03-10-2005, 09:48 PM

So I need the correct adapter, depending on design, six or eight bolts, a coupler, and then deal with the driveshaft issues, etc. Really I meant what do I need to get it in the truck. It's not running, so I don't care about driveshafts (yet). I had a 400/205 and sold it with the 85 K30 I was parting out. Still kicking myself for that one... I am going to look at an 83 K30 crewcab dually tomorrow at lunch. 454/400 and 205 I believe. It's got Alcoa wheels and looks like fairly decent black paint. Thanks again!

1976K5CHALET · 03-17-2005, 01:59 AM

Take a peek over at offroad design.com...he explains all the variables rather well.

DW

crosby · 03-17-2005, 07:44 AM

Hi Doug, thanks for the info. I heard from another source that I may not need a coupler... first I have to pull the tranny and existing xfer case out, measure the output shaft. Thanks for the help!

03-10-2005, 11:16 AM	#1
crosby Registered User Join Date: Aug 2004 Location: New Hampshire Posts: 437	NP205 in 76? K20 - what do I need? I am trying to put a NP205 in my mid 70s 3/4 ton 4x4. It has an 87 body and bed, but the frame is rotted in front of the rear spring mounts. So I bought another frame, and plan on putting the drivetrain in before I pull the body over. I have the original? Th400 and NP203 in it (full time ) and want to put a NP205 I picked up for it when I got the frame. I have discovered the transfer case adapter I need is expensive, and don't know what else I need. Isn't there a coupler in there too? I am not concerned about driveshafts or speedo cables yet, but what do I need to make the 205 work? Thanks very much for any help you guys can provide. __________________ Crosby 1978 Chevrolet K10 stepside NH

03-10-2005, 07:52 PM	#2
77gmcjoe What do we get for $10? Join Date: Oct 2004 Location: Beardstown, Illinois Posts: 341	I've just put a 400/205 into my truck, so maybe I can help. I had a 400/203 combo I was going to use, but ended up finding a rebuilt 205. After finding a 400/205 adapter (got lucky there), I discovered the tailshaft of the tranny I had wasn't long enough to mate with the 205 tcase. The adapter between my 400/203 was about an inch thick, where the 400/205 adapter was about 6 inches thick. BTW, the tailshaft of a correct 400TH goes directly into the 205 tcase, no coupler needed. You do have to have a 205 that has the correct input, there were several different styles. Again, luckily, I was able to get the correct 400TH with the longer tailshaft to mate with the 205. You'll need a 205 shifter as well, it's totally different than the 203 version. I know you said you weren't worried about driveshafts yet, but I'll tell you that mine are being modified right now (rear lengthened, front shortened). Can't wait to get them back so I can finally test drive it! All in all, it was quite a PITA, but I'm hoping in the end it will be worth it. Joe __________________ 1977 GMC K25 400/400/205 1989 Chevy Suburban R1500 350/700R4 (work beater) 1994 Chevy K3500 dually 454/4L80 1996 Corvette LT4 350/ZF 6 speed 2000 Bonneville SSEI Supercharged 3.8 Liter V6 1966 Chevelle 2 door sedan (Needs major repair )

03-10-2005, 08:27 PM	#3
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	good luck finding the correct version. Depending on what kind of adapter you find for it (early figure 8 or later 6 bolt circle), you will need either a long (fig 8) or short (circle/6) 32 spline female input gear 205, as well as the shaft for the tranny like Joe mentioned. both of these were only found in K30's. another solution is to find another kind of 205 case (10 or 27 spline) and have the bearing hole machined for the 32 spline gear (which are larger than 10 or 27), then buy a 32 spl gear (~$150) and put it in. then, you need the correct adapter...so it would be easier to just find a 400/205 combo, iow. good luck! __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

03-10-2005, 09:48 PM	#4
crosby Registered User Join Date: Aug 2004 Location: New Hampshire Posts: 437	So I need the correct adapter, depending on design, six or eight bolts, a coupler, and then deal with the driveshaft issues, etc. Really I meant what do I need to get it in the truck. It's not running, so I don't care about driveshafts (yet). I had a 400/205 and sold it with the 85 K30 I was parting out. Still kicking myself for that one... I am going to look at an 83 K30 crewcab dually tomorrow at lunch. 454/400 and 205 I believe. It's got Alcoa wheels and looks like fairly decent black paint. Thanks again! __________________ Crosby 1978 Chevrolet K10 stepside NH

03-17-2005, 01:59 AM	#5
1976K5CHALET Senior Member Join Date: Jan 2003 Location: Grand Junction, Colorado Posts: 611	Take a peek over at offroad design.com...he explains all the variables rather well. DW __________________ Doug Wright aka K5NUTT over @coloradok5.com Owner of http://groups.yahoo.com/group/ChevyK5BlazerChalets Certified K5 Nut

03-17-2005, 07:44 AM	#6
crosby Registered User Join Date: Aug 2004 Location: New Hampshire Posts: 437	Hi Doug, thanks for the info. I heard from another source that I may not need a coupler... first I have to pull the tranny and existing xfer case out, measure the output shaft. Thanks for the help! __________________ Crosby 1978 Chevrolet K10 stepside NH



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