Outer Limits 4x4 Board

I know it is not to much trouble to fit a 14bt into a cruiser, but I have herd that there is a bit involved in making a 15bt fit in. Can anyone tell me what is involved or give me links to anyone who has done it. I have done a search on this forum and havent come up with anything.
Also could you tell me of advantages/ disadvantages, say, compared to the 14bt or 13bt.
Cheers.
Dave.

I think the 15bt is very rare to find parts for and expensive to fix engine wise