How many does it take to change a light bulb ?

Why are you even asking? Did you read post # 8 and go on the Sylvania website? From the site it looks like an example of 2017 Prostar could have either LED or Halogen. LED was likely an upgrade. Did you watch the video link? If you do you will see where the halogen bulbs are, what they look like, and how to replace them. If you don't see the halogen bulbs then you have LED which is unlikely. You asked for a link and was provided one. Last, you don't look like a new user to the site, and should know that when people try to help you it is a courtesy to hit the thumbs up/Thank icon.
If you still don't know then take/post a pic of the headlights from the outside and also raise the hood and take/post a pic of where the headlight wiring is.
First bulb is halogen, second is LED.

 

open hood.

find light fixture.

try to access bulb.

pull out and look at it.

 

Some are really a bitxx to get at. My kids rented a car that had a headlight out, I was BARELY able to change it, as the wires were too short. I would imagine in a semi, it would be pretty straightforward.

 

some are, that's why I said try.

on some cars you almost have to disassemble the whole front end. lol

 

HA! My nephew has or had a Suzuki X7(?), and had to dismantle the entire bumper and grill to get at the light. Now why do you suppose that is?

 

isuzu trucks are fun. not

 

What model of International?

 

Its actually not a matter of year so much as how the truck was specified to have when new.
Ive have LED as far back as 2014 built in late 2013

 

maybe you have a bad or poor ground.??

with the constant opening of the hood, after a while the wires can crack and break..

i'd check the wiring loom/harness for a bad wire, before buying replacements, cuz if you replace what you have now, and they are still "dim" as you say..??


then YOU WILL be checking that wiring...