FB
My feeling on the hydraulics thing is that the person listing it is not familiar with RC. Note that they say that the plane is a large plane. You and I both know by todays standards that a plane like that would not be considered large as compared to the 30 to 50% size of planes we see today.
Not sure of what the plane is, but I feel like it is from around the later 70s to early 80s era due to the placement of the tuned pipe it had be designed for.