Originally Posted by DAF44
I replaced the 300 with the 310. Even though the factory 300 was a close fit, the 310 fit perfectly all around. You are right in that the 320 has a 3" longer top and a 1.25" longer base than the 310. May I ask why you want the 320? The 310 has a porcelain bowl and the swirl-jet bowl rinse just like the 320. You can also get an optional wood seat if you like. The 310 I installed included a hand rinse device. I paid $129 with shipping at Amazon a couple of months ago. We are very happy with the change.
The wood seat was something the DW really wanted, along with a sturdier base, but we were unaware it was an option on the 310. That would make it exactly what we are looking for. Thanks again for the helpful information.