first of all i would really appreciate any answer that i can get, i have a 1986 daihatsu rocky 2.8 diesel non turbo that i bough a few weeks ago, i want to make sure the engine its on really good shape for at least another 5 years or so and i would like to do an overhaul or change most of the main parts ( pistons,rings,cylinders,bearings,gaskets etc,etc,etc ). i would like to know if does inside parts of the engine como only for daihatsu rocky or can i fit any other parts as longs as is the correct size and measurements.

Now in the other hand would it be easy if i can buy a similar engine like a toyota hilux or any other similar engine and put it in. but my question is, if i do put another engine with transmission and transfer do i have to change differentials?