A comparasion shot of the 2 Squad 51's. The 1972 version is on the left, and the 1974 one is on the right. The Squads were Dodge "Dually" vehicles (named because of the dual rear wheels) used by LACoFD at the time.
This is the best side by side shot I've seen of them, and you can see the differences between the two.
There is a very subtle difference in the shade of red, the 1974 version has the white light on it (the Specs from LACoFD specified the white light, but they then changed their minds, but the show Squad had already been built).
You can also see the difference in the grill betwqeen the 1972 and the 1974 Dodge.
Of course, in the Pilot, Squad 10 also was completely different, as it was an earlier model Dodge (it's actually a bit bigger than our beloved Squad. It also had a white light and a different lightbar).
Both the 1972 and 1974 Squad vehicles were built by the studio and were owned by them, and then given to LACoFD. After the show, the Squad (complete with its "51" logo was used by the County as a reserve vehicle.
I love to think of the thrill that people would have gotten when it was used (and it was) and they realised it was the Squad - Squad 51!!
This is a very rare photo of Squad 51 actually In Service (with another LACoFD vehicle behind). As you can see, it's the 1974 vehicle. Also note that they have changed the wording of "Rescue Squad" to "Paramedic" (which which was how the Paramedic vehicles were labelled). The Squad that were not crewed by Paramedics, still had "Rescue Squad" on them.
For many years the same Dodge "duelly" vehicles were used but at one point they trialled using trucks like the big box ambulances. These were great practically - as they could carry the equipment better and if necessary transport a patient.
However - the Paramedics hated them. Not because of practical reasons, but because they weren't The Squad . (gotta "awwwwww" at those ridiculous sentimental Paramedics!!!)
The picture below is the current Squad 51, located at Station 51 at Paramount Studios.
Yes - still a Dodge Dually, but now a dual cab as well (though that rear cab doesn't look like it would enable a grown person to sit in there).
