Napa. Take ur old one in to match pics in the book .. They can usually overnight if u order before 2 or so,, My local Napa has books for older trucks with pics the computer doesn't show. Mine is a gates 21283 my son's K35 has a napa nbh7575
I just put one on my K15 .. I used rustoleum 2x black paint
/primer on the top and. Duplicolor rock guard on the bottom. I used a thin rubber mat material cut into strips for my strap pads. Have had good luck with this combo on previous builds
Another tank would probably work better. I thought about the same but using an electric air compressor and installing a power inverter to my aux battery for power
My old K10 was an airtank bumper , my 79 K20 was extended for the plow , and my current K15 . I cut horns of a donor truck n extended the bumper to add a receiver on the front .