Hi Goach!
Is the bed off the 1-ton already a hoist/lift bed? Hydraulic with a PTO-driven pump and cylinder? (if so, does your truck have an SM420 transmission or the 3-speed?) Or a newer electric system? And how much "later" is the 1-ton? Is the 1-ton a dually? If the frames are same width, etc, you might be able to just remove from the one-ton and bolt to the 3/4-ton. A tape measure is your best friend here.
You may already know this ... but ... Just be aware that it will be really, REALLY easy to dangerously overload your 3/4-ton with that bed. The hoist mechanism, if original to the 1-ton, is going to add weight. The bed will add more weight. And then whatever is left over (subtracted from your truck's rated Max Gross Weight) will be available to you for payload ... which won't be a lot. So do the math and see if it is even going to be worth it.
Just food for thought....
I
