3 on the tree or TH400????

[thisolechevy]

Hi guys I have a '69 K-10 with a built 327 and I am now coming into a dilema, I want to take the truck to the track and race it a couple of times just for fun and want to know what type of trasmission you would suggest. The truck currently has the old 3-speed on the column that is very tiresom to drive but is a great theft deterrrant!! :-) I have a chance to purchase a used but in perfect condition with 51,000 miles on it TH400. It is in great cond. and was just pulled the guy is asking $200 for it. Should I do the swap? and is it possible? remember I have the transfer case for 4-wheel. Can I swap transmissions?

[HeavyD]

I would do the swap myself. I like autos, but if you want to keep it a standard at least convert it to a floor shift...much easier to shift.

[mrein3]

I've said it before and I'll say it again. The best thing I ever did for my truck is swap the original 3-speed on-the-tree out for a th350 auto. You are right, the column shift is a great theft deterrant but in my case I was the only person I knew who could drive it. I have friends who drive straight-sticks all day long who couldn't drive it.

Now regarding your question:
You need to locate a th400 that was originally in a 4x4. You need the factory part between the tranny and transfer case, called the "adapter". You need the transfer case that came with a th400 from the factory. As you may have guessed by now your best bet is to get everything from one donor.

The th400 will stand up to anything and everything you can throw at it but it is also the most expensive setup to buy. And the hardest to locate.

No offense but a built 327 isn't all that strong. If I was you I'd locate a th350, adapter, and transfer case, rebuild the tranny before you install it, then never look back.

[thisolechevy]

Thanks MREIN3 No offense taken, I know its not all that powerful it just sounds good!!! :-) he he I did find a setup out of an old 4x4 with all the adapters and everything but with a bad TH400 transmission (big crack right down the bottom) I can get the setup for $150 + the TH400 from a friend still worth it?

[mrein3]

Originally Posted by thisolechevy

Thanks MREIN3 No offense taken, I know its not all that powerful it just sounds good!!! :-) he he I did find a setup out of an old 4x4 with all the adapters and everything but with a bad TH400 transmission (big crack right down the bottom) I can get the setup for $150 + the TH400 from a friend still worth it?

That would be a big fat YES!
If the "good" th400 is out of a 2wd you need to find a good friend who works on trannys. You need him to take the "bad" th400 apart and get the output shaft out. Then have him put it in the "good" th400. The way I understand it the output shaft is just about the first thing you put in when you rebuild and reassemble an automatic transmission. Not a job for a backyarder like myself.

I know a local farmer who has over 200k on a th400/np203 in a mid-70s pickup. The way he takes care of stuff he has no business having equipment still working with that much age/miles on it. He pulls loaded grain wagons out of muddy fields, huge stock trailers, all kinds of tranny killing stuff with it and it won't die.

Personally I'd stay away from the np203 but it obviously works. The th400/np205 is bullet proof. What transfer case are you getting for $150?

[special-K]

Whatever you do,you`ll need to get rid of the little transfer case that sits behind the 3spd manual.The autos & 4spds came through with NP205 t-cases.On the 327,that advise is simply not true,offended or not.The 327 was available from factory with as much as 375 hp.There ain`t nothin`a 350 can do that a 327 can`t.Don`t forget ,the factory only upped the cubes to compensate for increasing necessity to de-tune by way of federal mandate.

[crazy longhorn]

I love a stick trans myself......but will say that the 400 turbo is the only trans I have ever seen to run 1/4 MILLION miles without an overhaul! I am running some "screamin" gears under my longhorn (6spd Richmond)....I love it, but when it comes down to an auto trans, I say 400 turbo all the way....if you need overdrive, a vendors on the back will make you "bullet proof". We all love chit that flat works......a 400 T, + Vendors, will handle far more power on the street/strip than a good 700-R4 .....the complete mess wont be cheap tho..... crazyL

[mrein3]

Originally Posted by special-K

Whatever you do,you`ll need to get rid of the little transfer case that sits behind the 3spd manual.The autos & 4spds came through with NP205 t-cases.On the 327,that advise is simply not true,offended or not.The 327 was available from factory with as much as 375 hp.There ain`t nothin`a 350 can do that a 327 can`t.Don`t forget ,the factory only upped the cubes to compensate for increasing necessity to de-tune by way of federal mandate.

Sorry about that. I was assuming his 3-speed already had a NP205 behind it. Mine did. I sold my tranny and adapter to another board member with the same combo so at least two of them were built. Besides that a fire breathing dragon of a 327 would have done in that 3-speed a long time ago.

No matter what is there you are better off getting a t-case from behind a transmission that you want to swap to.
From a NP205 point of veiw:
All manual transmissions had a 10 spline output shaft. The np205 behind it had a 10-spline input shaft.
th350s have 28 splines, the np205 behind them have 28 spline input shafts.
The th400 has a 32 spline output shaft and, of course, the t-case behind it had a 32 spline input shaft.

On the 67-72 4x4 models, the only ones I researched, the ONLY difference in a drive line that came with a NP205 is the transmission and adapter. ALL the tranny/adapter/t-cases interchange IF THEY ARE SWAPPED WITH A COMPLETE DRIVE LINE FROM A DONOR. In other words if you have a 3-speed manual and want to swap to a th350, you need a th350, th350 to NP205 adapter, and a NP205 with a 28 spline input shaft. The cross member they sit on, the hole in the transmission hump in the cab, and the drive shafts are ALL THE SAME. You drop out the tranny, adapter, t-case, and replace it with the complete setup from a donor. GM made the length difference in the adapter so the t-case shifter and therefore the hole in the hump are in the same spot. This also made all the drive shafts the same length.

You can change the input shaft on the np205 but that is more money. And if you do that you still have to find the correct adapter. Personally I think you are better of just finding a good donor and swap in the complete setup.

Further, I would replace the drive sleeve and the oil seals in the adapter. The seals in the adapter keep the fluids where they belong. The sleeve can get a groove in it like the front oil seal on a small block engine. Too much groove = transmission fluid going in the transfer case or gear oil going in the transmission. Not a good thing. The time to replace those items is when they are sitting on the ground waiting to get installed.

[thisolechevy]

wow thank you so much for your research and input!!!! and beleive it or not I have never lost a race to any 350's even with 327 and 3 on the tree combo. Its still mean!!! so I guess I will be replaceing my t-case and tranny this upcoming week.