*PLUMBERSSTOCK EXPERT* responded:
Hello! In response to your inquiry about the Mars 21787 Check Valve Replacement Kit, yes, this will fit the Mars 21786 lift pump. Please see the specification sheet under "Resources" for reference. If you're interested in purchasing the Mars 21787, simply click "Add to Cart" and enter the required information and you'll be all set. Please don't hesitate to contact us if you have any further question about this check valve. We thank you for choosing PlumbersStock.com.