The same way you fix almost all other official-content related problems! This thread probably belongs in the "Questions and Support" forum, but here's the normal response: Of course you can try removing all of your mods first rather than doing a clean re-install first.
the easiest thing is to start the game in safe mode first. so you can make sure that you game files are corrupted or not. if the d-series is back , you can remove/disable outdated , not needed , or incompatible mods (or simply reomve every mod one by one) and check the vehicle selector each time you delete/disable something. if the d-series isn't visible in safe mode , you'll most likely have to do a clean reinstall