Where do I put new transmission fluid in an eaton 15 speed?

Need help new at this. Idk where to put the tranny fluid on my 15 speed.

 

Jack the cab up and there is a dipstick next to the gear shift. Then take the stick out and pour the brake fluid in until full

 

Should be a plug on side of transmission. It’s full whe it starts running out or you can feel it with your finger.

 

When it starts running out.. finger can reach to far down. Plug should be on the drivers side of transmission about half way up the side

 

What would cause some trailer lights to randomly go out when I just got it fixed 2 hours ago. All orange lights have gone out. But red ones are still there. Please help asap got runs to load and it's dark

 

The orange lights don't usually come back on until 5 am.

 

7 way plug. Brown wire is tail lights, black wire is clearance lights IIRC.

Check fuse/circuit breaker in truck. If trailer clearance light fuse/breaker is popped only with trailer connected, you have a wire grounding out in the trailer. If it pops with trailer connected or disconnected, wire in the truck is grounding out.

All fuses/breakers good, look for broken/corroded wire in clearance light circuit.