Yes, I think around Dec 1974. Now I remember Sin Boon Wah, I think he got promoted to MG and he later moved to Govt related company buying arms for the SAF, and he later made headlines someone tried to bribe him in favour of arm sales.
I left SG in 1981, and therefore, unable to recall whether Sin was promoted to MG. I did read about him moving to a GLC, and the alleged bribe which he declined and reported to the authorities. But I do recall Boey was a BG (who was a CPT, and the Brigade S3 when I was a 2LT at HQ 2 SIB), and then moved to Singapore Power, and thereafter to MRT.
I did hear rumours that Boey was the Chief of Army, and was considered to be the next CDS, and declined, which made way for Ng Jui Peng (1st batch OCS) to be CDS.