The black truck sides you see on my AS-16 are from a FA-2 They're the same size as the original truck sides that came with my RS-27 which were gray. ( I drilled and tapped the bottom screw mount black truck sides to work with my old style top screw mount trucks. )
PN db-2260001-0 https://www.mthtrains.com/db-2260001-0
( for 2 axle truck )( PRR )( # 9618 )( # 9619 )( # 9618B ) https://www.mthtrains.com/30-2173-1
https://www.mthtrains.com/30-2173-3
I'm 99% sure MTH doesn't have a different truck for the Sharknose since the truck side width to height proportions
seem to be the same.