which truck

Hey I've been flat bedding for about two years and I'm gonna be ready to purchase my first truck in summertime. I've raise my credit to just over 700 and I have 6k right now for a truck down payment. My think is I'm picky and I know I want to put 10k down and have all flatbed equip paid for cash. My question is which truck should I get first? Which avenue go down for this?Here is some of my requirements: 240 in wheelbase, otr sleeper(dont care how long as long as it has the cabinets) and I need an emissions truck because I want to roll to California often since I live in Phoenix. Ideally this truck would have or be able to have super singles, and get a bare minimum of 7 mpg total all miles. I dont care how fast it accelerates or how well it does on mountains. As long as I can get good mpg, and have a reliable truck I'll be happy. I'm looking to only spend 80k or less and have a payment of 400 or less. mpg is much more important to me than speed. I prefer cummins and I prefer 14 to 16 freightliners but I've never driven a cascadia with a cummins so I'm not sure if it's a good idea to get one of those. I like kw and x15 too but they are at the upper end of my price limit and want to explore something with lower payments. ideally my truck will have a 10 spd, and around 250k miles. another thing is that while I'm not afraid to get dirty, I have absolutely no mechanical background at all. I always want to learn more about the trucks I drive but I'm clueless so assume I won't be to useful for myself in that department in the near future. any advice at all will help. some trucks I'm looking at are cascadia 1r to 16 with isx and 300k miles or so and 10 spd, or a kw t680 18 with x15 and paccar automated at around 300k miles. I'd really like to get the cascadia because they are closer to the 60k range, let me know what you think about that or if there is a more reliable truck for the price that I could look into.

 

yea I think the dd13 could be an option but since i pull 40k plus usually it probably would need 450 hp and lower gear ratio for better mpg, right? i dont really know how to spec an engine, but i do know dd13 cascadia with the previous body style are fairly cheap