I converted my E320 Natural Gas over to Liquid propane and i DID NOT CUT A HOLE... just as DAN mentioned your opening up a can of RUST...!! I just used a very thin rubber cushion under the tank. I also don't use the Tank bracket as mentioned above... i purchased my Propane tank from COSTCO and...
This is the Liquid propane model ...where you will compare parts https://www.weber.com/US/en/help/schematics/browse.aspx?model=2251001
I believe your looking for part number # 38
here is a link to Convert BBQ from NG to LP ... https://tvwbb.com/showthread.php?77007-E-320-Genesis-conversion-Natural-Gas-over-to-Propane-!!!&highlight=Kelvin
I ended up going with the Whole Manifold replacement, once you get the New LP manifold it only takes 15 minutes to install.
Note...
These are the screws that are on the END of the Burners ( left hand side) ... the Weber E 320 is the Right side controls ...so the 3 burners are from left to right
Well i took everyones advice and used Steel Wool and Simple Green on the Cover of my Weber E 320 which is 10 Years old... here are the pictures.
Before...
Okay i tried rotating the screws around and i got the Center screw with the washer all the way in, other 2 not so much. I do realize my Weber E320 is 10 years old and your correct I'm lucky they came out.
i'll try a little lubrication on them... it might help them to go in just a little more... i hand threaded them in with my finger and then used a Flat head screw driver i could get maybe 1 to 2 revolutions of the screw thats it. I did not want to use the socket head on them...
Here is the Schematic... https://www.weber.com/US/en/help/schematics/browse.aspx?model=3851001
the 3 screws i need are part number 88217... having a hard time finding them!
It's what they call the hardware for the burner tubes ---
32 88217 Hardware for burner tubes, Genesis '09
any help...