The sp ed archives have the letters. I would ask for a full and complete evaluation including psychological, learning disabilities, sensory integration disorder, speech and audiology evaluations, IQ testing and anything else suggested in the sample letters. Do not limit it to just psychiatric testing. You should also seek a private evaluation for these things. A private evaluator answers to you. The school staff who will do the testing answers first to the school. If they find problems or suggest accommodations then the school will likely have to provide them - and that costs money and involves changing the status quo - neither of which is in the school's view of their interests (NOT that they will ever admit it!). Most of us have found that school evaluations are NOT complete and miss MANY things. School evaluations also look at what will impact education, not the student's entire life. Private evaluations look at their entire life. Insurance should pay for much of the evaluations. If you do not have private insurance, apply for the state kids insurance - most of this WILL be covered by them. Don't automatically assume you won't qualify. The guidelines are more generous than MANY people are aware of.
The sp ed forum archives will cover this and explain how to send the letters, etc... Start creating a Parent Report if you don't have one already. It is a document that you create to keep all of your child's records, evaluations, etc... in one place. A few years ago some of the moms here created the outline - the link in my sig will take you to it. It will help as you start the evaluation process, I promise!
REad up on the sp ed archives and post over there with questions - they are the real experts on the sp ed laws and how to get what your child needs from the school.