under dash wiring harness compatibility.

[Tduff01]

I have a 1978 K20 Scottsdale 350 4 speed. My under dash harness has unfortunately been hacked up from some previous owner. I have an under dash harness from a 1980 1-ton Chevy, I don't know anything else about the 1980 truck. My question is will these under dash harness just interchange and I can just plug n play with the 1980 harness in my 78? If not what issues will I most likely run into? Any help will be greatly appreciated. Will be working on the truck this weekend.
Thank you in advance for any help or information.

[hatzie]

People change from the class cartridge fuse to ATC panels all the time. 

1978 & 1980 actually used the same three bulkhead plugs to mate the cab and engine compartment sides of the firewall.  Download the wiring manuals for 1978 & 1980 to compare the wiring pinouts.  You can re-pin the bulkhead plugs if you have to.

[Tduff01]

Thank you. I will be working on it this weekend. We will see how it goes.