I would go with either one of the Aks. I would go with the 74, the polish ones are good and cheap the Ammo is cheaper than the 7.62 and you can get Tapco mags that work well.
go with a highpoint 995ts. they can be found used for under $200 and new for $250-275. They are SUPER accurate and have a life time warranty with no questions asked. They also have them in 40 and 45 if that fits the rest of your collection better. IMO they are really the perfect truck gun because they are rugged and accurate and the warranty. I have one my self and since shooting mine 2 of my friends have bought them and they list them (as i do ) as the most fun gun to shoot that they own.
I got a newer Ranger a few months back. 01 Edge supercab 4x4. Made me sad when my gun rack wouldnt work in the back window. It was a sad day. Next time I buy a truck i will have to bring the rack with me. Go for the underfolder