I can see from your pic, someone attempted a partial rebuild and not a very good one at that. Below are some places to buy new if you go that route. Rebuilding what you have most likely will be cheaper.
Here are some links from places I have bought from that sell new door units. There are more places out there, just I have not bought from them to know their service.
If you buy one, you will get the entire outer frame and all with it. If you remove the trim inside, you can measure the actual opening in the camper. I suggest you call them to confirm the new door unit will fit in the rough opening. The actual outer door frame will be slightly smaller than the rough opening. I am not totally sure the door sizes they list is the actual door itself or the rough opening dimensions. I have bought many camper items, just not an entry door yet.
Lippert Components makes them too. And it may be cheaper to buy direct from them. If you go with this brand, call them and get a quote and the freight.
This catalog lists them on page 56, square corner entry doors. It is a 50 meg PDF file, but it lists all the standard sizes and they will make you custom sizes.
Lippert Customer service number is here. https://support.lci1.com/contact
I bought a new cargo door from them last year that I knew they made, but did not have on their online store. They had no issues selling to me, just I had to do a call in order verses a web order.
Amazon sells the LCI door, I do not know if this is your size, they have other sizes listed https://www.amazon.com/Lippert-Compo...omotive&sr=1-1
And so does Tweetyí https://tweetys.com/search.aspx?find...er+entry+doors
There are also the RV surplus places in Elkhart. They sell brand new items that are over stocks or phase outs from the local RV manufactures. I have been to, and bought from all 3 of these places. You can often get these types of things lots cheaper than retail new. But shop around, sometimes they charge almost full price. It all depends on the item. Get your size and call them. You can build entire camper from what they have. Only a fraction of the items are listed on their web sites.
Ebay also sometimes has them. Search under " Square corner RV entry door "
Hope this helps
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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