OK, here are the three problems:
1. The existing toilet (Seeland Traveller model 511) is 34 years old and no longer made.
2. Base bolt pattern is four bolt. Almost all current RV toilets are 2 bolt.
3. "Sit height" (floor to top of toilet seat) measures about 10-1/2" Entire unit sits on a riser of about 8" that cannot be removed or altered because the black water tank is directly below.
SO?? What should we get? The 34 year old unit has a visible crack in the bowl. The flush ball no longer holds water. The foot lever sounds really bad when activated.
We've been very happy with the Dometic 321 (shorter version of the 320 series that work on the riser). Easy install when replacing the Seeland, nice sturdy ceramic bowl, and replacing the toilet seal is a breeze,
https://www.youtube.com/watch?v=weB0fSbgW-0
I didn't realize that there was so much difference in the parts and pieces in a Foretravel. My 88 ORED has a two bolt thetford galaxy low line, same size riser and that's probably because they both have the thetford 45 gallon angled delivery tank. When that gave up the ghost I replaced it with the new galaxy low line.
So, is the Dometic 321 a four bolt mount or a two bolt mount? Nothing in their ads says anything about the mounting bolt pattern/quantity.
The Dometic 321 ad at etrailer.com states "2-bolt installation", backed up by excellent photos.
https://www.etrailer.com/RV-Toilets/Dometic/DOM99FR.html
So add another $100 for the four bolt to two bolt conversion. Still as sturdy and stable as our old 511?
WOW, what a savings. And I still get the same old rotating ball mechanism design that has failed repeatedly in our coach.
Upset about the whole issue? I guess I am. After six tries last year while camping the toilet no longer leaks on to the floor but quit holding water about a month after we got the coach home after a winter in storage. And now the actuator mechanism squeals when I step down the lever.
Most of the thetford parts are available
I think the complete toilet is also.
I like ours and have swapped the flush valve and flush blade seal.
Our is as stable and sturdy. What I really like about the Dometic is the abilty to replace the toilet seal without having to remove the whole dang toilet. Quick, 5 minute change. We are FT and the original seal was fine for 2 years, so I have no complaints.
I have a thetford dunny in mine Norm, No idea how many bolts hold it in,
I will have a look tomorrow when Im down there at the storage place,
Brian I'm betting it's the same setup as mine if it's a thetford though I've never seen a four bolt dunnie. Maybe it's like a GM engine with a four bolt main made for heavy duty work ?
You can replace the bolts and just use two or change out the base plate to make it work. You don't need a 4 bolt pattern with the new commodes. Keep in mind that the Dometic, when the pedal breaks, you have to replace the toilet. There is no fix for that! I know, as I had to replace ours this year after only 2.5 years of putting a new Dometic 320 in the coach. Was not happy! Called Dometic and they do not make a part for that pedal when the inside plastic breaks! UGH! Since you have the box that the toilet sits on, any low level toilet should work, just make sure the distance from the base to the back of any cabinet or wall will clear! If you want, you can send me photos and I will walk you through the process. Hope this helps!
In case someone else is looking, the 511 model is still available.
Dometic 511 Gravity Toilet, Ceramic, Low-Profile Height, White | 9108552967 (https://rvpartsusa.com/dometic-511-gravity-toilet-ceramic-low-profile-height-white-9108552967/)
511HS TRAVELER TOILET (https://www.environmentalmarine.com/dometic-sealand-traveler-511h-white-302651101/)
511+ Traveler, White - Marine Sanitation & Supply (https://marinesan.com/511-traveler/?gad_source=1)