Turbo 350 Information and Facts

[1low4x4]

Thanks for the Info

 

[tiredtiretodd]

How do I identify my tranny

I'm going thru my SB and trying to identify my tranny and transfer case. here's a pic of my t case to start.

 

[HotRodPC]

Looking like an NP203 full time case to me.

 

[marks86]

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heres a np205 see the difference
I can tell by the little plate with three screws in the middle

 

[tiredtiretodd]

You must be registered for see images

upload png
heres a np205 see the difference
I can tell by the little plate with three screws in the middle

Thanks marks86, I am looking into a NP205 that a buddy has laying around. I think he said I could have it for about $50 if I came and got it out of his yard.

 

[HotRodPC]

NP205 for $50 is a steal even for a slip yoke unit.

 

[garzas23]

What would be Dextron ll or better? Whats the best fluid alternative?

 

[Edhard_Stark]

I've been looking into doing a TH350C swap in my 79 K10 for better fuel economy and less heat in the trans. I figure it'll be cheaper and easier plus keep a stronger trans than a 700R4, however I know I won't get the same fuel economy as a 700R4 but the previously stated perks are more important to me. Are there any disadvantages to swapping to a TH350C? The truck will probably see a 350whp/400wtq~ LS swap or a SBC, so moderate strength would be nice or as close to a built th350 as much as possible. Can I keep my np203? I'm aware of the aftermarket lockup controllers, however is it possible to swap over the stock lockup components to a non-lockup truck, within reason? By that I mean cost and I don't want to swap over a bunch of drivetrain stuff and rewire the harness for it.

 

[HotRodPC]

I've been looking into doing a TH350C swap in my 79 K10 for better fuel economy and less heat in the trans. I figure it'll be cheaper and easier plus keep a stronger trans than a 700R4, however I know I won't get the same fuel economy as a 700R4 but the previously stated perks are more important to me. Are there any disadvantages to swapping to a TH350C? The truck will probably see a 350whp/400wtq~ LS swap or a SBC, so moderate strength would be nice or as close to a built th350 as much as possible. Can I keep my np203? I'm aware of the aftermarket lockup controllers, however is it possible to swap over the stock lockup components to a non-lockup truck, within reason? By that I mean cost and I don't want to swap over a bunch of drivetrain stuff and rewire the harness for it.

So you mean swap from a Th350 to a Th350C? Sure you can do that very easily and yes you can convert to the OEM lock up by finding a donor truck and robbing the small wiring harness and vac switch. Yes, your NP203 will bolt to the Th350C just like the Th350. Same adapter all. The only difference in the 350 and 350C is the input shaft, pump and valve body so none of the exterior characteristics are different other than the added plug on the driver side for the lock up wiring harness.

 

[Edhard_Stark]

Great, thanks for the info HR!

 

[CJL85]

i have a decent question what is the difference in the valve body from a th350 and a th350c i have a 1985 c10 with a th350c i have the eletrical connector but nothing is attatched to it also ther are holes in my fire wall and no vaccume solenoids is it possible this trans has something done to it ?

 

[wilrab]

Hey HotRod,

I have a th350 question. I purchased a newly rebuilt 400 HP/400 torque engine for my K10 and wanted to have my th350 rebuilt at the same time to hold up to the new motor.

I contacted a well recommended transmission repair shop in town and the owner asked me to take pics to the bell housing because there is a heavy duty version that came with 4x4 models that has a thicker bell housing and bolt holes for braces. From the pics I sent it looks like the one in my truck was replaced at some point with a passenger model th350. From doing some searching online I found the model I'm looking for sometimes has a K or HD stamped on the bell housing. I guess the thinner bell housing of the passenger version tends to crack at the top of the bell housing when paired up to the cast iron np205 transfer case. Have you heard of this being the case?

I am finding a very hard time finding one of these HD versions for him to rebuild and also don't see a ton of information about them so I was hoping to get your opinion.

Also I tried putting up a post in the Wanted section but I guess I don't have permissions to post there.

Thanks in advance.

Bill

 

[HotRodPC]

Hey HotRod,

I have a th350 question. I purchased a newly rebuilt 400 HP/400 torque engine for my K10 and wanted to have my th350 rebuilt at the same time to hold up to the new motor.

I contacted a well recommended transmission repair shop in town and the owner asked me to take pics to the bell housing because there is a heavy duty version that came with 4x4 models that has a thicker bell housing and bolt holes for braces. From the pics I sent it looks like the one in my truck was replaced at some point with a passenger model th350. From doing some searching online I found the model I'm looking for sometimes has a K or HD stamped on the bell housing. I guess the thinner bell housing of the passenger version tends to crack at the top of the bell housing when paired up to the cast iron np205 transfer case. Have you heard of this being the case?

I am finding a very hard time finding one of these HD versions for him to rebuild and also don't see a ton of information about them so I was hoping to get your opinion.

Also I tried putting up a post in the Wanted section but I guess I don't have permissions to post there.

Thanks in advance.

Bill

You can post in the Classifieds section after you hit 50 posts. There is a reason why the forum owner does this and it is for a good purpose. It's not so much for the WANTED section though, more for the SELLING section.

A well built Th350 should hold up to 400/400 fine. It won't last as long a Th400, but you should get good service out of it if you keep it cool. Yes, the 4x4 units are a bit beefier around the bell housing area. The standard Th350 should hold up too for light to moderate 4x4 provided you have all the support rods in place, like the one from the Tcase to the bell housing bolts and your trans/transfer case mount is in good shape. For moderate to heavy wheeling, then you'd probably want to go ahead and hold out for the beefier Th350 case.

 

[wilrab]

You can post in the Classifieds section after you hit 50 posts. There is a reason why the forum owner does this and it is for a good purpose. It's not so much for the WANTED section though, more for the SELLING section.

A well built Th350 should hold up to 400/400 fine. It won't last as long a Th400, but you should get good service out of it if you keep it cool. Yes, the 4x4 units are a bit beefier around the bell housing area. The standard Th350 should hold up too for light to moderate 4x4 provided you have all the support rods in place, like the one from the Tcase to the bell housing bolts and your trans/transfer case mount is in good shape. For moderate to heavy wheeling, then you'd probably want to go ahead and hold out for the beefier Th350 case.

Thanks for the quick reply HotRod. I think I will hold out for the beefier th350 but they seem pretty scarce. If I can't find one soon I'll look into a th400

 

[HotRodPC]

yes, they're a bit scarce. Keep in mind, if you swap to a Th400, then you'll have to have a different input on the Tcase, different driveshafts etc since the length is different as well as the spline output from 27 to 32.