01 Flagstaff 823 questions

[HD86]

hello all! I recently was given a 2001 Flagstaff 823 popup from family friend. It needed some work as the back end was damaged. It sat for over 2 years after the incident so everything has that musty smell. We removed all of the fabric and cushions and gave it a deep cleaning. We tossed the mattresses and want to replace them but forgot to measure them exactly. The camper is now in storage for a little while as we are too busy to work on it but want to get the mattresses ordered. Can anyone with help with the dimensions? Thanks in advance. I'm really looking forward to reading and learning from all of the great posts about my new to me camper!