Yes they do. The problem with converting them is many times the bumpers are part of the chassis, so to complete them used or aftermarket chrome must be aquired. Some, like the Ford GT or Dino Ferrari, can be put right on the chassis. Some of the posts are somewhat shorter, but spacers can be used to acheive the correct height.
Certain valences were also modified with slots, gashes and dashes to accomodate the coaster chassis; so there may be some "residual ugly" after converting to plastic slotcar bumpers. Some guys just murdify the existing metal bumpers to fit.
Although not a "Cigar Box" thing; some "Speedlines" had enlarged enlarged wheel wells and no accent painting or glass installed.