Holding Tank IP35 Replaced

We replaced the holding tank and all lines on our IP35 two times so far. Both times were as a preventative measure: first time was the second year we owner here in 2002. Second time was 2009 as we thought 7 yrs was long enough on the lines and tank. Each time we used the factory EZELL aluminum tank. Each time we used Odor Safe hoses and this time it was odor safe plus hose and the Dometic/Sealand fittings. On the IP 32, 35, 37 the tanks are easy to get to as they are in the settee and come right out.