You can use any year you like that has a power steering box (sector) that's shaped like yours. 73-87 would probably be the best ranges in the 1/2 and 3/4 ton trucks. As far as metric, it's just the line fittings that are metric. That's why I suggest getting everything from one vehicle, no mixing and matching and you get brackets and hardware that you wouldn't get from buying new. I would go with used parts as long as they look like they aren't leaking. These old boxes last forever as long as they aren't ever wrecked. And reseal kits are still available too. I like to buy the old 73-87 trucks that are rusted to the ground and scrap them out. Most have V-8's, automatics, power steering, etc. I just aquired a 78 3/4 4X4 for free that has a fresh crate engine and trans. that's very rusty but is now my plow truck. There's tons of them out there that can be had for a couple hundred or less.
That's the way I would go,
Scott
