Now you have me reminiscing. The last unit with a rubber boat on top (prior to the three TAC Units in 2000) was the original HazMat, organized as a combination unit with Rescue Squad 3 in 1984. Photo is shop serial S-604, a 1966 Ford N850/Bruco , xRS-2, xRS-4, xReserve. It stayed around until 1988.
Kevin Byrne