It's not overly difficult to put in a factory one, you just have to completely strip out the dash, good excuse to clean out all the dust anyway, but you do have to drill a few extra holes in the firewall, there are indents where the holes go to make it easier, it would be ideal to have the motor out if only to save your back from bending over the engine bay, make sure your ac components are clean and in working order before you instal it cause dust and grit in the system will mess it up real quick, check with your local auto air con mechanic, if they are any good they'll help.