Yes 24p you were on the money. The first number in the call sign identifies the type and the second number is less important. For example in the Lofty group Stirling used the 1 as the second number for their appliances while Bridgewater used 2 and etc. While Brigades like Mt Barker went sort of in size ie 51,52,73,74,25.
The 25 was a command vehicle with no water.