the ford ranger never came with a Yamaha V6. That was the Taurus SHO.
the ranger get the Vulcan V6 what was widely utilized in the Ford/Mercury range
It's not engine braking because there is no throttle body like a gasoline engine (except for gasoline engines that do not have a throttle body). The closing of the throttle body means it's under vacuum, which dramatically slows down the engine.
On diesels, there is no throttle body, thus the engine cannot produce vacuum, so engine braking is inefficient. The Jake brake is a compression release system. So, at the top of the compression stroke, the Jake brake opens up the exhaust valves, releasing the hot compressed air, thus no power is transmitted back to the pistons, it that's how the Jake brake slows down an engine.
there are some areas that prohibit jake braking, which can be subject to a fine.... then you cannot use your jake brake and rely on your actual brakes.
The first fuel injected 6 in the Ranger was a Yamaha engine which was only available for a year or 2 as the sales rep made a big deal of it for the power increase over the 4. I know I had one it was a 3l V6. Don't think I have the sales brouchure anymore. No Air, Extended Cab, Metalic Blue, Chrome Insert in Tailgate and Chrome bumper because it was 5 speed manual (which was a surprise when I got it as it was the a base model) 4x2, couldn't afford the 4x4 as it was my first new vehicle just after graduating University.
My wife to be learned to drive on that truck and managed to shift into reverse from first without touching the clutch , luckily the engine stalled and no parts dropped out the trany. She also laid 50 6oft of rubber because of the stalling issue. She hated that truck for the standard, however every other standard has been easy since that one.
You can still tell which one have it with the manual as they are always reeving the engine at the light to get going. Have to or they stalled. Used to make drinking money from those that drove standard by betting they would stall the truck. They always did on the first attempt. The SHO engine in the Taurus came a lot later.