Contour Line at specific position

Hi all,

A rather basic question but as i m a begginer in grasshopper i cannot figure out the correct way to make contour lines of a surface at specific location.
The way i m doing it right now is shown below. However if the slider exceeds a specific distance the curve from explode tree is different.

Ultimately, what i would like to do is give distance from XZ plane in panel (i.e 1000 , 2750, 6000) and extract the contour lines.
Any advise would be really helpful.

Thanks in advance

Attach your file and someone will help. Make sure you internalise all geometry.

Instead of contours, maybe what you want is plane intersections? Sec (Brep | Plane)

Thanks Joseph!