Pro tips: 

• Be sure to contact the Research Institution that you are working with early on in the process so that there are no delays gathering the cost estimate, LOC, and information concerning their portion of the project.  Because of the size of these institutions, particularly if dealing with academic institutions, it can be difficult to get all of the necessary forms and information on short notice.   
• It may be useful to supply the Research Institution with a draft of the LOC for your application package.  Providing a draft will ensure that the letter includes all of the necessary information and will make it easier for the RI to complete and return to you quickly.