From 350 trans to 400 transmission

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silverlostdog

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Jun 17, 2016
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Location
Hoouston
First Name
David
Truck Year
1977
Truck Model
C20
Engine Size
350
I have a 1977 C20 3/4 ton I'm in the process of swapping in a 406 small block. What will it take to install a turbo 400 Trans instead of a 350 Trans? Will I have to get a drive shaft made or is there one from another vehicle I can use.
Any info or assistance will be greatly appreciated.

Silverlostdog
 

74Blaze

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Oct 25, 2022
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Location
Nashville, IN
First Name
Gerald
Truck Year
1974
Truck Model
K5/Blazer
Engine Size
350
Not sure of the interchange with another vehicle, but if you need one made, I recommend Fort Wayne Clutch & Driveline. They've built several for me over the years and always have done a good job. They ship anywhere in the country.
 

NickTransmissions

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Location
Las Vegas
First Name
Nick
Truck Year
1987
Truck Model
R10
Engine Size
350
I have a 1977 C20 3/4 ton I'm in the process of swapping in a 406 small block. What will it take to install a turbo 400 Trans instead of a 350 Trans? Will I have to get a drive shaft made or is there one from another vehicle I can use.
Any info or assistance will be greatly appreciated.

Silverlostdog
Have your existing drive shaft cut and rebalanced or a performance driveshaft made ss mentioned above. Trans cross member will need to be moved back which is straightforward...
 

Ricko1966

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Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
What I normally do,build my combo,measure for a drive shaft and head to pik n pull armed with a tape measure. I can usually find something the correct length and replace the Ujoints. If you are lucky you may find another same wheelbase C series truck that came with a 400,grab it,and the driveshaft.
 

Craig Nedrow

NADAR UNDER THE RADAR
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Location
Washington State
First Name
Craig
Truck Year
1973 (have two), 1985
Truck Model
K10, K20, C20
Engine Size
350, 454, 6.2 Detroit
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I use a self built 350, 375 horse 454, six rear tires later, she still a peach
 

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