To be fair here BJ the 1400 is a wren 54 mk3 produced by Jetjoe it is not a similar design, I could use any of the parts from wren to replace ones in my turbine and likewise use any jetjoe parts in a wren.
This is really what it boils down to, I cannot comment on the other turbines 1800, 3000 etc.

Yes the turbine design goes back a long way, I have plans for a KJ66 which apart from some combustion chamber design changes could easily be an exploded view for a wren or jetjoe.
Other designs like the Hawk turbine are different concepts, but many are similar to the wren 54 layout and I bet there are others fundamently the same, but the big thing here which is causing the problem is an exact copy.