I have an old '71 FJ40, and it runs real good. It only has 66,000 miles on it. However, I would like to replace the stock straight six engine with a diesel engine. My only criteria is that it fit in easily. I'm not looking for lots of power, and don't care if it is a 4-5 or 6 cylinder model. Can anyone help as to what would be a good fit? Thanks.