We've had 2 RV shops attempt to get a part number for one of our holding tanks that has been leaking so we can get it replaced. After several weeks, they claim to have been unable to get the information. Yesterday, I sent an email to Monaco tech support ([email protected]) with the year, make, model, serial no. and VIN no. of our coach and received a reply this morning with the part numbers for all of our tanks. I have no idea what channels the RV shop was using but a simple email is all it took. So if you need any info on your older RV, try the manufacturer, you may be pleasantly surprised.