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Discussion Starter #1
Hello, I used to check these forums all the time but that was a long time ago and I stopped checking in.
I have a 1975 Super Sport El Camino that my father bought from a friend about 10 years ago as a project and first car for me. The Elky was made in Fremont, CA and has a 350 smallblock 2bolt main & 2 barrel manifold.

The car has become my primary transport for going to the store and I use the bus for everything else while I am in college. Recently however the first(and reverse) gear on my car/truck crapped out on me. I am looking to get it rebuild or replace it with a buddy of mine's transmission. I need some experienced people to fill me in on if this plan will work.

First, I am fairly certain that I have the turbo hydraMatic 400 3speed transmission (if it's stock) though I am unsure on how to verify this. Does anyone know?

Second, my buddy has a 76 or 77 Chevy Scottsdale 2 wheel drive 1/2 ton front 3/4 rear with a 350 smallblock. He is not the original owner and is not a gearhead so I do not know if it is stock. What should I be looking for when I inspect his transmission? Should I take pictures and upload them for you guys to see?

If anyone has any resources or information that would help a poor college student try to get his car back on the road would be much appreciated. Including any knowledge on average prices for the parts to complete this project.

Thank you so much in advanced for your help!
 

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Be sure to measure overall lengths when comparing,and the pick up is likely to have a different stall speed convertor even if the trans. are the same.TH 400 uses vacuum downshift while TH350 uses a cable.If you are not mechanically inclined make sure to research before attempting to swap.
 

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TH400 uses an electric kick down, 350 the cable - both have vacuum modulators. 350 on passenger side rear, 400 on passenger front corner.
 

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Discussion Starter #6
Hmm, ok so that means a THM should just bolt right in then? maybe a frame mount conversion? maybe longer vacuum tubes? how does the electric kick down fit in?
 

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a 400 is longer usually, depending on the tail housings on both, normally means a shorter driveshaft..

the front yoke is bigger..

youll have to move the trans cross member back about 6", usually..

you may have to get the flywheel and starter with the 400,, but
some 350 flywheels do have the dual torque converter bolt pattern..

the electric kickdown is purty easy, just a 1 wire switch on the throttle.. IIRC..

longer vacuum hose is easy..

heres some more on the trans lengths..
http://www.maliburacing.com/auto_tranny_id.htm

:texas:
 

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Discussion Starter #9
Thanks a lot gentlemen, you have all been a great help. I have to find some transport to go check out some transmissions (and shops) in the area including the one in my buddies Scottsdale. I will post with an update when I have one!
 

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There are "kick-down" switches available from Summit Racing, which I believe are actuated by the gas pedal linkage.

Not to rain on your ideas, but another TH350 would be simpler to use...

The drive shaft yoke behind a TH400 is bigger,like JJ said, and would need a U-joint to match both the yoke & shaft etc.....like 1310 or 1330, to a 1350....etc., and that's after cutting the shaft to the correct length...

It's all fun !!
 
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