Hi Mick,
Welcome to the site, The amalgamation of The Kings (Liverpool) Regiment and the Manchester Regiment was September 1958 at Warley Barracks, Brentwood.
Laburnum Street still exists today, (Manchester A to Z, page 77/ M4/5) it runs parallel to Langworthy Road between Spring Gardens and Wall Street next to Langworthy Park ,Salford, which in your grandfather's time would have been Highfield Reservoir.
Take care,
George.