From 350 trans to 400 transmission

silverlostdog · Oct 11, 2024

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 · Oct 11, 2024

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 · Oct 11, 2024

silverlostdog said:
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 · Oct 12, 2024

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.

bucket · Oct 12, 2024

It also depends on the length of the tail shaft, as well as if it's a fixed yoke or a slip yoke.

Craig Nedrow · Oct 15, 2024

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I use a self built 350, 375 horse 454, six rear tires later, she still a peach

From 350 trans to 400 transmission

silverlostdog

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