Product review (1 stars): Useless due to the way the combustion pan is attached to the tank.
Step 15 in the replacement instructions reads: "Insert tank into combustion pan. Place large gaskets around large combustion tubes., then place metal retainer rings over tubes and tap down until pressed firmly against back of combustion pan." There are actually four metal retainer rings - two on the backside of the combustion pan and two on the front side. At the factory they probably have a special jig to hold the tank while using a hydraulic press to slide the rings over the large combustion tubes. In the field I had to use a hammer and small chisel to 'tap' the rings down and over the large combustion tubes. The rings fit so tightly that doing it in the field is almost impossible. I eventually got them on but it took me about four hours and a thousand 'taps' to get it done. Extremely difficult!