According to the floor plan, for options 113, 131, 208, 833, for your 2018 Holiday Rambler Vacationer 35P, then you have a King Eurotop measuring 72" x 75".
With that information, the etrailer eDream RV Mattress # e64FR is the correct size replacement for your Rambler. view full answer...
I wasn't quite sure the exact measurement you were referring to in regards to "diameter of the rim alignment ledge" for the Trailer Idler Hub Assembly for 2,000-lb Axles # AKIHUB-440-2-2K so I took a number of measurements of this hub.
If you take a look at the accompanying photo I made you can see each of the measurements. I have also added a link to a video review of this hub for you to take a look at as well. view full answer...
I attached pictures that have all of the dimensions for the RearView Safety Flush Mount Bracket # RVS-421 that you referenced. Overall it's 7.875 inches wide and 6.125 inches tall. view full answer...