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Old 12-18-2012, 04:32 AM   #1
shipma2
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th350 to th400

how much is a shop gonna charge me to have a th400 put in my 78 k10? its to low for me to do sense I dont have a lift what all will need to be done
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Old 12-18-2012, 05:49 AM   #2
bk2life
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Re: th350 to th400

Quote:
Originally Posted by shipma2 View Post
its to low for me to do sense I dont have a lift what all will need to be done
pull the motor with trans, swap trans, put assembly back in if that is an option?

question, why 350 to 400 anyways?

price id say no less then 600 for a shop to do it.
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Old 12-18-2012, 06:20 AM   #3
shipma2
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Re: th350 to th400

cause it has a 454 in it the th350 crash shifts and broke a tooth off my ring gear in my rear diff
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Old 12-18-2012, 06:32 AM   #4
donut
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Re: th350 to th400

Not going to quote a price, but looking at the same swap for my old K-20, it wasn't cost effective even with the 2 trans. in my yard. bk2life pretty much hit it. It can be a straightforward swap IF you have means to adapt or acquire the turbo 400 transfer case.

the turbo 350 and 400 do have different output shafts, size (may need driveshafts "adjusted") and the adapter.

When I looked into it, it was more cost efficient to have the turbo 350 built to what I wanted, though if you have a donor vehicle with the turbo 400 drivetrain....
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Old 12-18-2012, 06:57 AM   #5
K30_dump
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Re: th350 to th400

Hello,

I agree with the above, would be more cost effective to have the TH350 built .

To swap to a TH400, you'd also need to wire an electric kickdown switch. Original switch was part of the gas pedal, but some aftermarket installs use a carb-mounted switch.

Being a '78, I'm assuming you have a 203 transfer case now. As mentioned, the adapter and input shaft on the case would need to be changed and they are RARE. You'd also need the correct output shaft in the transmission, as the 203 takes the shortest of all TH400 tail shafts (also extremely rare). Advance adapters may have a solution, not sure...

Either way, the TH350 can easily be built to take big block torque. Heck, my Dad ran one behind a 454 for many years in his K30 T-tag. That weighs 6,800 lbs and the transmission held up for nearly 20 years .

Hope this helps,

Joe
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Old 12-18-2012, 11:20 PM   #6
Rubble
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Re: th350 to th400

I don't know why not having a lift makes any difference,pulled a 700R out of my 85 K20 last year no lift.Just had to jack rear end up a bit to get tranny out from under truck on tranny jack.Sometimes you just have to be creative....
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