Can't give you the lat and long but I can give you some directions and things to watch for:
IF heading south:
The highway as you are leaving Los Mochis crosses a river. On the LEFT as you cross you should see the large Pemex called La Pilarica.
You need to be in the RIGHT lane. Exit right, and turn back towards the river then at the river RIGHT again and under the bridge. As you come out from under the bridge you can't miss La Pilarica ahead and on the right, on the corner.
Here you have a choice: Straight ahead and then turn right through the diesel pump islands (Gas pumps islands come first) OR Turn right then LEFT into the station, this will be behind the pumps and buildings and there is a lot of parked trucks and trailers NOT in the fenced lot. Carry on between the buildings and the parked vehicles and you will come to the fenced lot which used to be signed "Pension"
If heading North:
As you approach Los Mochis watch for large REST AREA and Area de Descanso signs. These used to start 10 or 15 kilometers ahead.
When you see the highway ahead begin to rise up hill from the flat this is the bridge and you need to be in the right lane. Exit is a hard 90 degree RIGHT followed by a hard LEFT and you will then be approaching La Pilarica on your right. You can enter here between the buildings and the parked rigs. You can access the pumps from here too if you need to.
These exits used to be a bit rough. It's been almost 2 years since we were there but I doubt things had changed much.
As you can see I am a slow typer: Briansue's post wasn't there when I started to type!