It took about 30 minutes (including the time it took to clean up the junk that had accumulated over the months under the range floor). Easy to do. Just removed about 12-odd screws in order to remove the cosmetic plates/covers the covers, etc., to access the unit, took off one wire at a time from the old unit and connected it to the new unit, then put everything back.
Required both Phillips head screwdriver and star bits (for 4 of the screws).