They will not. The 2018 is a new body style. Here is the front and rear liners in black for the 2014, https://www.sharptruck.com/weathertech-floorliner-digitalfit-front-and-rear-fits-vehicles-wdual-floor-posts-retention-device-black-443461-442712
This is the set for the vehicle in
black, https://www.sharptruck.com/weathertech-floorliner-digitalfit-front-and-rear-wtwo-retention-hooks-on-driver-side-black-extended-cab-441761-440472
tan - https://www.sharptruck.com/weathertech-floorliner-digitalfit-front-and-rear-wtwo-retention-hooks-on-driver-side-tan-extended-cab-451761-450472
grey - https://www.sharptruck.com/weathertech-floorliner-digitalfit-front-and-rear-wtwo-retention-hooks-on-driver-side-gray-extended-cab-461761-460472
I do not have a carpeted liner, but this liner is very unique and not like the hard plastic ones,
https://www.sharptruck.com/3d-maxpider-kagu-cargo-liner-black-55
Yes, here are the options for only the 3rd row
Black - https://www.sharptruck.com/weathertech-digitalfit-floor-liners-446075
Cocoa -https://www.sharptruck.com/weathertech-digitalfit-floor-liners-476075
Tan - https://www.sharptruck.com/weathertech-digitalfit-floor-liners-456075
Grey - https://www.sharptruck.com/weathertech-digitalfit-floor-liners-466075
There are trim to fit mats that can work, https://www.sharptruck.com/weathertech-avm-universal-floor-mats
There is not a custom fit liner or mat for the 1968 pickup