I had thought that Well-X-Trol pressure tanks all had diaphragms. It turns out that there are some with a replaceable bladder. And some of these are listed as "full acceptance", and I guess those can accept a higher pressure range. The bladder tanks seem to be aimed at the commercial users.
http://www.amtrol.com/media/documents/wellxtrol_asme/MC10008_01_14_WXT_ASME.pdf lists model numbers and other data.
http://www.amtrol.com/media/documents/wellxtrol_asme/9017097_06_14_WXT_Replacement_Bladder.pdf has bladder replacing instructions.
http://www.amtrol.com/media/documents/wellxtrol_asme/MC10008_01_14_WXT_ASME.pdf lists model numbers and other data.
http://www.amtrol.com/media/documents/wellxtrol_asme/9017097_06_14_WXT_Replacement_Bladder.pdf has bladder replacing instructions.