Transformation: Remove the cannon and mount. Fold the back of the vehicle back 180 degrees to form the legs. Stand with the underside facing forward. Fold the front of the ambulance back revealing the face. Pull the arms out to the sides and peg the photon pistol into the inside of the fist. Extend the legs.
Like all the other Protectobot limb robots, bar Streetwise, First Aid has his peg holes on the inside of the hand rather than the top. Indeed I had a First Aid gun floating around in my spares box for years before I realised what it was, the odd design making me think it was for a different toy (possibly a Headmaster junior head gun) or for a different toyline entirely! First Aid's robot mode reveals some red plastic upper legs and the typical Scramble City/Special Team square head. The chest is a slightly darker red which was first made of metal and then latterly as a plastic part. The same colour part and change is made to several of the other Protectobots including Hotspot making me think there's some gang moulding going on with these toys. First Aid's sole points of meaningful articulation are his shoulders, which turn, while his knees do bend but the lower legs are one piece and the hips don't move so that's useless for doing anything with! Like Streetwise and the Stunticons his vehicle mode weapon is useless in this mode which is a shame. A 5mm plug in the back of the folded back vehicle front would allow the cannon to be mounted pointing over his head as a medical laser.
First Aid also serves as a limb for Defensor.
Leg mode: From vehicle mode fold the front of the ambulance back. Attach a foot to the rear of the vehicle and attach to the knee of Defensor. Fold the front of the vehicle back.
Arm Mode: From vehicle mode fold the front of the ambulance back and fold the head under the vehicle. Flip the back half of the vehicle around 180 degrees. Peg a fist into the hole at the bottom of the wrist. Extend the arm. Attach.
I don't like the look of this arm mode: the exposed outer part of the lower arm and the folded back vehicle front sticking out to the sides annoy me. So here's my version: Fold back the front of the ambulance, fold the head down and fold the front of the ambulance back into place. Attach hand to the hold in the back of the ambulance meant for the cannon. Attach. Yes it's a shorter arm, but it looks much better to my eye *and* it gives Defensor some elbow articulation with the forearm being able to fold in.
First Aid was sold as Protectobot P4 and as part of the Defensor giftset. In Japan he was released as Transformers toy C-75 and was part of the C-76 Guardian giftset. First Aid has had one re-issue as part of the gold carded European Classics line in 1991.
Safety is very similar to First Aid with a whiter white and the chest plate now becoming orange plastic as per Fly-up (Blades and Fire Chief (Hotspot).
As for a Decepticon version...... how about calling him Chaser (as in Ambulance Chaser) and painting him black or a dark blue as if he was wearing a suit like a lawyer?