The <Model>reconditioned engine is a replacement for your existing engine. It has been stipped down, the parts checked and renewed where necessary.
The existing engine, requires disconnection from mountings, cables and pipes. Depending on which Brand and model the old engine will require disconnection from the gearbox before or after removal from the engine compartment. On some vehicles the gearbox will remain in position on others it will be removed and refitted when the whole unit is removed with the gearbox still attached. The reconditioned engine may be purchased complete or Bare. Complete needs no parts from your existing engine. Bare, meaning that it will need parts from your existing engine. This needs to be clarified.
All parts being used from the old engine for the Bare reconditioned engine should be checked and replaced as necessary. Engine mountings may also need to be replaced.
The reconditioned engine will come with a warranty, this needs to be clarified as to the warranty length and coverage detail.