I'm not sure where you can find a door to fit you camper premade off the shelf. But I do know where you can order one.
In Feb, 2019 I ordered "I believe" the same large cargo door from a T264SR which Sunline used in the T2363. These doors are made to order, takes about 2 weeks, or did in 2019. Not sure with Covid but here is the place to start. I think mine was around $135 or $165, can't recall exactly. Was a lot cheaper then I thought.
Lippert Components (LCI) has a division that makes cargo doors. Start with this parts customer service number.
LIPPERT COMPONENTS, INC #039
401 S BEIGER ST
MISHAWAKA, IN 46544-3206
They cannot identify with your Sunline. They have no record of it. But if you request that they can build you a cargo door for your camper, they can help you.
They need the style of door and the rough opening of hole in the wall of the camper.
See pics. This is my old door next to the new Lippert door.
This is the rough opening, the size of the wood frame hole in the camper. And they need to know that the hinge is on the top. They make then a lot of different ways.
And the new door installed
They will send you a form to fill out to make the door and it has a bunch of check boxes that you may or may not know the answers too as they make hundreds of different doors.
See these pics I sent them to start my door ordering process. This hones in on the style etc. Check to see if your door matches these dimensions, if it does I can give you my order number, they can look it up and that may help you as it has all that info.
If your door checks out to have those dimensions, then give LCI this sticker number. You can email it to them even as it has even the manufacturing order on it. That long monster number has all the sizes, styles etc. of what they shipped me. It is a place to start even if yours happens to be a different size.
Hope this helps and let is know how you make out.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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