They may -- or they may not -- there is no requirement for a dataplate
on an airboat engine!
I'm guessing that John Smith is asking because the dataplate might be
the difference between being able to have it remanned and be certified
vs. just being another non-certified engine. Kinda like home
'remodels' where they knock down everything but one interior wall, then
build a whole new house around it. By keeping that one well documented
wall original, the builder avoids the tax consequences of construction
a whole new building vs. just 'fixing up' the existing.