Yep my mistake, the Oreca Viper and probably the Chamberlain cars as well, seeing as the '97/'98 version Viper needs the more modern shape, should go on the LMRT version. The pics below give a clear difference in visual spec.
'96 Viper (Verde model):
'98 Viper (LMRT model):
With the Marcos, again there are visual differences between the two versions.
'96 LM600 (Verde's version):
'98 LM600 (BorekS version?):
So yeah my apologies didn't notice the differences in the cars. But seeing as there is models for the '98 skins, at least they are skinnable on close enough the right version.