In a mild/moderate LLD class, you can have up to 10 students with no aide (just teacher). You can have 11-16 students if you have a teacher and an aide.
In a severe LLD class, you can have 8 with no aide, and 9-12 students with an aide in the room.
I think the classifications of students entering an LLD class would be Other Health Impaired, Communication Impaired, Cognitively Impaired, or Specific Learning Disability. (I think.)
I have an MD class (Multiple Disabilities), where truly any classification fits (unfortunately in my case, because my autistic students really need an autistic class where the size is limited to 6 students and the ratio is limited to 3:1). In an MD class, you can have up to 8 students with no aide, and 9-12 with an aide. I have 12, with aides in the room.
Here's a link to NJ Administrative Code for Special Education, for future reference: