Whether we are talking about propeller aircraft or jets, there is no single speed that will provide Max endurance, Max range and Best Glide Speed."
Max endurance occurs at the speed where fuel flow in minimum. Max range occurs where the tangent touches the appropriate (power or drag) curve.
When gliding (with engines shut down) it doesn't matter what kind of engines we have, they are not contributing anything useful.
Aircraft in flight are constantly dissipating energy as they move forward against the drag force. The purpose of the engines is to provide energy to the aircraft, to replace the energy that is being lost. When the engines fail the aircraft has a limited store of kinetic and potential energy, which can no longer be replenished. This energy will be used up during the subsequent glide. To maximise glide endurance we must fly at the speed at which the stored energy is dissipated as slowly as possible. Energy dissipation rate is power, so for maximum glide endurance we must glide at Vmp.
If you sketch the forces acting on an aircraft in a steady glide you will find that the tangent of the glide angle = D/L. For maximum glide range we need minimum glide angle. Tangents increase with the angle, so for maximum glide range we need minimum D/L. Minimum D/L means maximum L/D, which occurs at Vmd. So best glide range speed is Vmd.
So best glide endurance occurs at Vmp and best glide range occurs at Vmd. These points on the curve are the same as for propeller aircraft. So for gliding use the Power Curve just as we did for propeller aircraft.
Looking at all tree situations (props, jets and gliding) we have.
1. Vmp, where (C_L)^(3/2)/C_D) is a maximum, gives best Glide endurance and best prop endurance.
2. Vmd, where (C_L/C_D is a maximum, gives best prop range, best glide range and best jet endurance.
3. 1.32 Vmd, Where TAS / Drag) is a maximum, gives best jet range.
BUT REMEMBER
All of the above ignores the fact that SFC is not constant. So in the real world the required speeds are likely to be slightly different.