I'm sure you can find aftermarket units if you do a google search. However, you could get most of the parts from a junk yard. Cost depends on the particular yard. You will need to get mounting brackets, compressor, (2) coils (one in front of the radiator, one in by the heater coil) some additional ductwork under the dash, change the dash parts that contain the vents, control components under the radio, hoses, new housing that holds the heater coil and AC coil mounted on the fire wall. I may have left something out, but I would guess it would cost a few hundred plus the time to rip the old system apart and install the new one. Not a weekend job but you don't need to do it all in one shot. Break it into doable steps that don't take your truck out of service. If you can find someone parting out a truck with AC in it, that might be the least expensive.
Good luck,
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