After a few complaints that the Double Deck trailer by Kevin Devine (imported to ETS2 by DJaz) was no longer working I decided to update the model and make it standalone.
The download can be found on the Other Mods page, full credits can be found in the read me file.
Permission was given by Kevin to release this mod.
The mod has been left open to allow you to add/change/remove the cargo and to allow you to use your own skins.
IJ's Mods 
finally thanks!! a few bugs/nags the skins are very bright and would it be possable to make the trailers longer and move the hook up point closer to the cab so there isnt such a big gap?
It’s an unsupported mod, that’s why it’s on the “other mods” page.
I am not the author I just updated it and made it standalone. It is released as is. Beyond trying to keep it updated to new game releases I won’t be touching it.
What are the first steps in the direction of editing the skins of the trailer? I just want to add a few things to improve the skin.
In the original mod, there is a Stobart double decker curtain sider. Is this still in it as i have this mod installed and have not seen it?
There has
never
been a double decker in the mod.
There is a Jumbo curtain (white Tesco) and a solid box trailer (white stobart).
Try to reduce the size of pmg & lod file…too big (00:01:23.464 : [resource_task] Default temporary buffer is insufficient while reading ‘/vehicle/trailer/doubledeck/trailer.pmg’ with size 25431480
00:01:42.252 : [resource_task] Default temporary buffer is insufficient while reading ‘/vehicle/trailer/doubledeck/lod_01.pmg’ with size 25515640
00:03:27.863 : [resource_task] Default temporary buffer is insufficient while reading ‘/vehicle/trailer/doubledeck/trailer.pmg’ with size 25431480) Tnx
Mod is not compatible with 1.24 and will not be updated.