I have a Sealand 510+ model.  The dealer sold me the seal with the overflow hole in it.  I do not believe I have an overflow.  Some say this is a universal seal.  My question is can I use this seal which is part number 385316140 or do I need to order the one with no overflow hole 385311462.  My concern is that it may leak but I do not think any liquid will get to the hole.
Any one with personal experience?