This simple mod adds the East Empire Company logo to all the relevant strongboxes added by the Dragonborn DLC. Ported to Skyrim SE from Skyrim LE, original mod by UlithiumDragon (ported with permission).

Ported from Skyrim LE with permission given by the original mod author UlithiumDragon (as well as Gamwich), original mod page link found here: East Empire Strongbox Logo.

What I updated in this mod port:

• Re-saved in the 64-bit CK and added all five vanilla game ESMs as masters to the mod by doing so.
• Flagged the ESP as an ESL.
• Added the correct bash tags (Deactivate and Graphics). You should deactivate and import this mod into your bashed patch in Wrye Bash ideally, so that only the Graphics changes are imported, and nothing else (giving it greater compatibility with other mods that also modify the East Empire Company Strongbox record).
• Meshes and textures have been optimised for SSE when necessary in Cathedral Assets Optimizer version 5.3.13.
• Carried forward the USSEP respawn flag for the East Empire Company Strongbox.
  

You only need to download and install one main file if you want the best textures, which has the Gamwich textures in either 1k or 2k resolution. If you want to use the old texture originally made by UlithiumDragon, then just download and install that optional file only. If you want every strongbox in the entire game (including non-East Empire Company ones) to be replaced by these models, then only download and install one miscellaneous file instead.

Original mod page's contents:

[Update]
Gamwich was kind enough to provide me with a version that uses his new Rustic East Empire Logo. I have uploaded it.

[Description]
I always enjoyed collecting the East Empire Pendants found during the Dragonborn DLC, as there aren't very many vanilla scavenger hunt quests. While on my umpteenth playthrough, I got over-the-top irritated at the lack of a difference between the East Empire Company Strongboxes and the regular strongboxes. The textures are identical. It seems Bethesda had time to create a unique pendant model, but couldn't spare the 5 minutes I spent slapping a proper East Empire Company logo onto the strongboxes. This mod aims to fix that issue.

[Functionality]
Because both the strongboxes have the same mesh file, it was necessary that an .esp file be created for this mod. Otherwise you'd see the East Empire Company logo on all strongboxes in the game. I made sure that the East Empire Company Strongbox was the only thing I edited with the Creation Kit. I also double checked with TES5Edit, so there is no reason for any issues with this mod.

[Mod Compatibility]
This mod should and will be compatible with any mod that doesn't edit the model used by the East Empire Company Strongbox.

[Optional Versions]
I added an optional version that replaces all strongbox textures with this logo. Using this method doesn't require an .esp so make sure to use only one!