If your Webasto Air Top EVO 40 heater is a 12v or 24v this fuel pump would be suitable.
A fuel damper uses a diaphragm to regulate and smoothen the flow/pulses of fuel and compensates for a drop in pressure as the pump operates. It is not always necessary to have a fuel damper.
An alternative fuel pump with a damper can be found at https://www.butlertechnik.com/item/Webasto/heater-Fuel-Pump-Air-Top-2000-STC-or-Thermo-PRO-9024802A/5F9