Tirediron.
Unless you wish to redesign the bath area in your 64, the only practical
replacement toilet is a Thetford 20920.
You will however, have to open up the hole in the bench, as this toilet must
drop down through that hole.
Additionally, the toilet will be above the top of the bench by an inch or so.
Many have tried other solutions, but no one has ever reported any answers,
other than what we do at our shop, as well as ship outs.
Andy
Inland RV Center, Inc.
www.inlandrv.com