1977 C20 4L80E swap

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lcfman

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Aug 13, 2018
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Location
Murfreesboro, Tenn
First Name
Geary
Truck Year
1977
Truck Model
c20
Engine Size
350
I am considering a 4L80E swap in my 77 C20 with 454. My question will the trans fit without any body modification to the transmission/firewall area? Any other helpful comments welcome. thanks
 

Catbox

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Jul 12, 2018
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Location
Just Outside of Portland Oregon
First Name
Peter
Truck Year
1979
Truck Model
C20 Silverado Camper Special
Engine Size
461
He has tagged me as I am planning to swap a 4L80 into my truck as well.
Mine is a manual SM465 truck, so I have a bolt in tunnel cover on my floor.
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You do not mention if you are an auto or manual already.

I do not think that I will have any issues with the transmission case size in my truck.
I cannot verify if an auto will be the same.
I would not think there would be any issues though.
 

CheemsK1500

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Texas
First Name
Paul
Truck Year
1984
Truck Model
K1500
Engine Size
305
For a 4L80E to go behind a 454 and actually shift, you'll need to either do a manual valve body conversion (This effectively turns your automatic transmission into a full time semi-automatic transmission) or you can install a stand-alone shift module and retrofit a throttle position sensor to your carburetor to retain automatic shifting.
 
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