Since you're not working with an aluminum tank, you're probably in much better shape than most of us who've struggled with our metal tanks. Should be much easier/safer to remove the screws/fittings from the poly, though I personally haven't worked on one. Regarding replacement gauge, the WEMA's are definitely the chit! much more durable and reliable, and supposedly more accurate as well. Only way to be 100% sure you order the correct gauge though is to pull the existing one out and measure the depth of the tank manually (ruler, stick, etc.) since you likely can't even guarantee the one in there is the correct gauge to be matched. Would give you a chance to check the bottom of your tank for "gunk" too. Then you can order with confidence any pretty much any gauge you want that's 1" shorter than the depth of your tank. Definitely take some time to clean up the pickup fitting and see how bad she really is. The guys are probably right in saying it should be replaced too.
