Involved in the biosynthesis of one of the two 2,6-deoxysugars, dTDP-L-oleandrose, attached to the macrolactone ring oleandolide to produce the aglycone antibiotic oleandomycin (PubMed:10770761). Probably catalyzes the conversion of dTDP-4-keto-2,6-dideoxy-alpha-D-glucose to dTDP-4-keto-2,6-dideoxy-beta-L-galactose. Antibiotic biosynthesis. Belongs to the dTDP-4-dehydrorhamnose 3,5-epimerase family. In contrast to other members of the family, lacks the conserved His active site in position 60, which is replaced by an Thr residue, suggesting a different reaction mechanism.