402/4 speed factory setup? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rickstores69chev · 03-15-2005, 03:51 PM

Hi everyone,

I am pulling my th350/np203 combo out of my 69 truck. The tranny needs some seals or something. Leaks oil all over the place. Was rebuilt by the previous owner. Not sure what they did although it shifts fine. The original tranny was a 4 speed according to the options sticker in the glove compartment.

I have considered going back to a 4 speed and mounting up to a np205. What 4 speed transmissions can I use with a np205?

I can get a complete setup from a 2wd Chevy bellhousing pedals, etc.. Don't know that it would be compatible or mount up to the np205. The gentleman said his truck is a 402 ,4 speed set up from the factory. Did not know what model or anything. I would like to find out if this might work. It is ideal since all the compnents are there.

1969 GMC · 03-15-2005, 04:26 PM

the only GM 4 speed to ever come with the NP205 is the SM465, which you may or may not have. there is a slight chance you may have a NP435 in your truck, but its not likely. anyway, to convert a 2wd SM465 to 4wd, you need the correct rear bearing retainer, and a new transmission mainshaft (which will require a complete teardown of the tranny). the 2wd tranny has a 35 spline rear output with threads on the end for the ujoint yoke. the 4x4 rear outputs have either 10 or 32 splines, depending on transfer case.
it would be easier to start out with a 4x4 tranny in the long run.

rickstores69chev · 03-17-2005, 01:39 PM

Ok, that is great information. Do you know which 4 speeds will bolt up to a np205? Now I am thinking I better stick with my auto unless there is a 5 speed possibility. Would make a better driver. I assume the the 4 speed is probably the same rpm as a th350 on the highway @70mph. I am just exploring all my options so that I make a thought out decision.

1969 GMC · 03-17-2005, 04:58 PM

anything can be made to bolt up to a 205 these days, but from the factory the only 4 speed GM offered with it was the 465.

you are right the 4 speed will give you the same number of RPM on the highway as the TH350, they both have 1:1 final drive.

the only 5 speed that ever came attached to a 205 from the factory was the Getrag 5 speed offered in dodge pickups in the early 90's...they are breakage prone. however there are adapters nowadays to mate pretty much any transmission to the 205. you could PM "ryanroo" he has a NV4500 5 speed mated to a 205 that he just bought. its pretty sweet.

rickstores69chev · 03-18-2005, 01:56 AM

I think fixing my rebuilt th350 that leaks oil like crazy sounds like a good thing to do.

Previous person did some interesting stuff. It shift fine though. Supposedly, they rebuilt it. I can tell someone stripped off the hex on the transmission lines. Tightening with channel locks or something. I definetly going to pull it. I have found a th350.205 combo. The 205 has 25,000 miles since the rebuild. The th350 it is bolted to is in good running order according to the seller. No history on miles other than it ws working awesome when it was pulled.

Is it easy to replace the seals on the tranny? I never messed with automatic transmissions. I have done a few clutches in manuals.

I am trying to decide which tranny to use. I know the one I have now works. The other one works to. Either way I should do some seals and servicing while they are out I suspect.

Appreciate any thoughts from the experience!

Thanks!

**JIMs70GMC** · 03-18-2005, 07:09 AM

Is it the front and rear seals? If so they are straight forward to replace.

**MJN** · 03-18-2005, 10:23 AM

NP435 were Ford transmissions. The tranny on the 402 would be a SM465 but like 1969 GMC said, the main shaft needs to be swapped in order to make it work with a mated t-case. You could leave it as is, make a mount for a divorced transfer case and run one of those. You best bet would be to find a tranny/t-case combo and just swap it in behind the 402 and run it.

1969 GMC · 03-18-2005, 01:47 PM

Quote:

Originally Posted by MJN

NP435 were Ford transmissions.

Actually they were Ford, Dodge, International, and GM transmissions.
I don't know why they were an option for GM, but they did come in close and wide ratio varieties, and only in 2wds.

rickstores69chev · 03-18-2005, 07:14 PM

I think it is front and rear seals. Not coming out around pan, although it does look like it had leaked around the dipstick tube. The torque converter is exposed. Don't know why other than I think a shield is missing. The t converter is coated with oil. Looks like it is coming out around there. I will shoot some pictures and post it. I would love to learn how to replace these. I really can not afford to pay labor rates to do this.

Thanks Again!
Rick

03-15-2005, 03:51 PM	#1
rickstores69chev Registered User Join Date: Feb 2005 Posts: 40	4 spd 2wd w/np205 Hi everyone, I am pulling my th350/np203 combo out of my 69 truck. The tranny needs some seals or something. Leaks oil all over the place. Was rebuilt by the previous owner. Not sure what they did although it shifts fine. The original tranny was a 4 speed according to the options sticker in the glove compartment. I have considered going back to a 4 speed and mounting up to a np205. What 4 speed transmissions can I use with a np205? I can get a complete setup from a 2wd Chevy bellhousing pedals, etc.. Don't know that it would be compatible or mount up to the np205. The gentleman said his truck is a 402 ,4 speed set up from the factory. Did not know what model or anything. I would like to find out if this might work. It is ideal since all the compnents are there. Last edited by rickstores69chev; 03-16-2005 at 02:33 AM.

03-15-2005, 04:26 PM	#2
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	the only GM 4 speed to ever come with the NP205 is the SM465, which you may or may not have. there is a slight chance you may have a NP435 in your truck, but its not likely. anyway, to convert a 2wd SM465 to 4wd, you need the correct rear bearing retainer, and a new transmission mainshaft (which will require a complete teardown of the tranny). the 2wd tranny has a 35 spline rear output with threads on the end for the ujoint yoke. the 4x4 rear outputs have either 10 or 32 splines, depending on transfer case. it would be easier to start out with a 4x4 tranny in the long run. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

03-17-2005, 04:58 PM	#4
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	anything can be made to bolt up to a 205 these days, but from the factory the only 4 speed GM offered with it was the 465. you are right the 4 speed will give you the same number of RPM on the highway as the TH350, they both have 1:1 final drive. the only 5 speed that ever came attached to a 205 from the factory was the Getrag 5 speed offered in dodge pickups in the early 90's...they are breakage prone. however there are adapters nowadays to mate pretty much any transmission to the 205. you could PM "ryanroo" he has a NV4500 5 speed mated to a 205 that he just bought. its pretty sweet. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

03-18-2005, 07:09 AM	#6
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	Is it the front and rear seals? If so they are straight forward to replace. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

03-18-2005, 10:23 AM	#7
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 3,052	NP435 were Ford transmissions. The tranny on the 402 would be a SM465 but like 1969 GMC said, the main shaft needs to be swapped in order to make it work with a mated t-case. You could leave it as is, make a mount for a divorced transfer case and run one of those. You best bet would be to find a tranny/t-case combo and just swap it in behind the 402 and run it. __________________ '51 South Bend Model "9A" '56 Chevy 3600 NAPCO '74 Chevy Cheyenne Super K20-restored on 37's '72 GMC Sierra Custom K2500- in progress '08 GMC Envoy Denali '12 GMC Sierra 2500HD Denali '17 GMC Yukon XL VCCA member #58596 http://www.nohrco.com

03-17-2005, 01:39 PM	#3
rickstores69chev Registered User Join Date: Feb 2005 Posts: 40	Ok, that is great information. Do you know which 4 speeds will bolt up to a np205? Now I am thinking I better stick with my auto unless there is a 5 speed possibility. Would make a better driver. I assume the the 4 speed is probably the same rpm as a th350 on the highway @70mph. I am just exploring all my options so that I make a thought out decision.

03-18-2005, 01:56 AM	#5
rickstores69chev Registered User Join Date: Feb 2005 Posts: 40	I think fixing my rebuilt th350 that leaks oil like crazy sounds like a good thing to do. Previous person did some interesting stuff. It shift fine though. Supposedly, they rebuilt it. I can tell someone stripped off the hex on the transmission lines. Tightening with channel locks or something. I definetly going to pull it. I have found a th350.205 combo. The 205 has 25,000 miles since the rebuild. The th350 it is bolted to is in good running order according to the seller. No history on miles other than it ws working awesome when it was pulled. Is it easy to replace the seals on the tranny? I never messed with automatic transmissions. I have done a few clutches in manuals. I am trying to decide which tranny to use. I know the one I have now works. The other one works to. Either way I should do some seals and servicing while they are out I suspect. Appreciate any thoughts from the experience! Thanks!

03-18-2005, 07:14 PM	#9
rickstores69chev Registered User Join Date: Feb 2005 Posts: 40	I think it is front and rear seals. Not coming out around pan, although it does look like it had leaked around the dipstick tube. The torque converter is exposed. Don't know why other than I think a shield is missing. The t converter is coated with oil. Looks like it is coming out around there. I will shoot some pictures and post it. I would love to learn how to replace these. I really can not afford to pay labor rates to do this. Thanks Again! Rick

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