Its so frustrating that alot of the retired loco and rolling stock have been retired and some of the workshops etc rely on assets that are no long available or have been included in other update so mean the files maybe located else where . Someone is missing a trick by not selling a Retired Pack etc. Or at least setting up a spreadsheet of where old stuff has been moved to in the new packs. It not necessarily obvious
Already a thread on this. Use LocoSwap to replace stock in scenarios https://forums.dovetailgames.com/threads/removed-steam-dlc-discussion.64992
I have also made a list of ways of buying many retired DLCS which you may be interested in. https://forums.dovetailgames.com/threads/ways-of-buying-withdrawn-dlc.57496/