Hi Bill, Thank you for initiating contact. The "Robust Fuel System Sender" is a design feature in the fuel pump/sender unit that can be identified by a specific code, such as "K53." It is a more durable version of a regular fuel level sensor, likely used in trucks, vans, or vehicles equipped for heavy-duty use. This fuel pump is for without that feature. If you're unsure if your vehicle requires a robust fuel system sender, consult your car's manual or contact the dealership for clarification. If your vehicle is without that feature, you can click on the link below for direct ordering to take advantage of our ongoing discount and limited stocks. Happy shopping. https://www.carparts.com/fuel-pump/airtex/afe3506m?can=CPGG4850_CSQA_20240503

Hi Richard, I'm pleased to assist you. I can't answer your question due to the lack of information. I suggest calling our parts specialists at 1-866-529-0412 to provide the vehicle information so we can help you look for the right part. We look forward to hearing from you. Have a good one.