The cap may have a L on it and yes they are two different sizes plus the low pressure line is usually larger. Since it's working somewhat, one can will be more than enough to top it off. Go for it.
This post is my opinion (free advice). It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.
Sold 04 Dynasty to our son after 14 great years.
Upgraded with a 08 HR Navigator 45โ...