Import files in the RPF archive
You can download OpenIV here: http://www.gtaall.com/gta-5/programs/60431-openiv-25.html

Use OpenIV to import the files from folder "01 - Import to x64e.rpf" in the archive [GAME FOLDER]\x64e.rpf:
levels\gta5\vehicles.rpf\bus+hi.ytd
levels\gta5\vehicles.rpf\bus.yft
levels\gta5\vehicles.rpf\bus.ytd
levels\gta5\vehicles.rpf\bus_hi.yft