Another day, another theory.
I think AJ is is an early Land Rover 90/110, which, if studied closely, appears to be fitted with extended breathing/exhaust tubing (snorkel) for passing through high water. 24 is a photograph of American Sherman tanks, used in the 1944 invasion of Normandy, which are fitted with large rear intake/exhaust ducts for coming ashore in high water. Therefore, I'll try: AJ-24, with the connection being vehicles modified for operation in high water.