Cat 336 ac help

I've got a Cat 336 with serial number CAT0336ECRZA00244 and I'm planning to pull out the evaporator core tomorrow to clean it. Does anyone know the exact amount of Freon I need to charge it back up with? Want to make sure I get it right when I put it back in.

The system is rated for 2.0 pounds (0.9 kg). You should be able to find this info on a tag somewhere around the inside of the cab door frame.

Thanks.