WIW 4L80E/NP208 tranny/transfer combo

[Down south truckin]

I have a truck with this setup in it and am having problems with the motor running rich so I'm considering switching to a carburetor and a sm/465/208 which is what the truck originally came with but a P/O switched it out.The p/o was a transmission shop owner so I'm sure the transmission and transfer case were checked out and should be in tip top shape.I'm not sure this is the route I want to go but would like to know what you guys think the combo is worth.Thanks in advance DST