I have a '98 Vanden Plas which needs an engine replacement, and i was wondering how i could identify the engine type in the car because i've been told to make sure i get the right one since there is the aj26 and the aj27. is that true? I have really not worked on this car and have only just started researching this. I was wondering if i could get some clarification. Also i was wondering if there would be any big issues if i tried to do this myself? any feedback would be great.