2018 - Camb E3 is ALS

[agent yo'range]

Engine 3 is now ALS! – As of January 11, 2018 Engine 3 became the
department’s FIFTH Advanced Life Support (ALS) unit. ALS emergency
care is now provided by Rescue 1, Squad 2, Squad 4, Engine 1 and
Engine 3.

from https://www.cambridgema.gov/~/media/Files/firedepartment/publicationsfolder/companyjournal/company_journal_86.pdf

this might have changed between 2018 and the present

also in 2018 - Squad 2 and Squad 4 changed from vans to light rescues