Th350 rebuild

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GAjoe

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Joe
Truck Year
1976
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K20
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Sbc 350
Question,

I am going to be pulling and rebuilding a Th350 and NP203 from a 1976 K20. This is going to be my first time buying a rebuild kit for both and have some questions on when sourcing parts, such as when buying internal parts for the tranny is there a difference due to it being 4wd vs 2wd or are the parts interchangeable?

New to rebuilding and would appreciate some guidance.

Cheers!
 

Rusty Nail

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YOU ARE lucky I got here first.



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I dont know for certain, but do not believe they are internally different.

However the 2wd vs 4wd cases are externally different for certain.

I had a th350 rebuilt last year and didnt get 1,000 miles out of it- at a great cost.

A 2wd trans converted for 4x4 installation.
Probably know better what NOT to do right? :rolleyes: don't do that.^^^

However when considering the next th 350 in proper 4wd case at an even GREATER cost, I chose a lower speed stall convertor than the 22-2500 I put in the last trans but primarily because I do a TON of idle/low speed cruising.
The new convertor is 17-2000 for use with 31" tires.

-Non-lockup convertor
-utilize a shift kit at the lowest "stage1/RV" setting available.
-use the biggest trans cooler you can find
-get a new adjustable modulator
-replace the detent cable with a NEW one.

Do those five things and it should last FOREVER - if it's built right.

AND junior, watch out who you choose to source information from IN THIS MSB because some of these @$$holes arent worth a damn when it comes to the supposedly simple 3 speed but they talk a good game.

Since you are doing it yourself, you'll prolly be okay, no tellin what that guy actually put inside of that wasted trans... See I bought the absolute best parts I could find and expected much better than one dollar per mile not unreasonably.

Hope this helps, but consider the source because you will get what you pay for.

That's my two cents' worth. ;)
Keep the change.
 
Last edited:

dhenderz

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Michigan
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Dennis
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K10
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327
This is the source I used as reference when I rebuilt my TH350

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