I remember there used to be a mod that was created by a modder by the name of Mal0 that replaced the Tactical Sight with the Elcan Specter. Unfortunately he deleted his profile and everything else with it, but I saw that a few people had reuploaded some of his mods, such as the:

EOTech for Projection RDS (https://modworkshop.net/mod/52142)

Carry handle and front sight mod for the CAR-4 (https://modworkshop.net/mod/51954)

PD2-style assault indicator (https://www.nexusmods.com/payday3/mods/147)

As far as I'm aware, the Elcan mod is the only one from his PD3 uploads that has yet to be reuploaded. If anyone out there still has the file, I'd greatly appreciate it you can share it on here (if it still works with the game that is).