Complex sentence: The one noticeable change was to Southern Pacific's "Bloody Nose" paint scheme--the serif font on the sides of the locomotives was replaced by the Rio Grande's "speed lettering", which was utilized on all SP locomotives built after the merger.
Split into simpler sentences: The one noticeable change was to Southern Pacific's "Bloody Nose" paint scheme. The serif font on the sides of the locomotives was replaced by the Rio Grande's "speed lettering", which was utilized on all SP locomotives built after the merger.