Depends on how much experience you have with all the procedures involved. You will have to drain coolant and discharge the a/c system, remove the a/c accumulator and brackets from the front of the firewall, disconnect the heater hoses, remove the dashboard from inside the cab, then remove the heater/a/c box. Disassemble the box to remove the heater core, then put it all back together. If you're fortunate, and have a little help, maybe 12 hours.