New results are presented concerning several optical centres having local vibrational modes in electron it-radiated and annealed 4H and 6H SiC. Some of these centres are common to both polytypes, others have only been found in 6H SiC. They appear, typically, after annealing in the range 1000° C - 1300° C. Additional results have been obtained about mode splitting from C-13 isotope enriched 6H SiC.