* Number of seats: The number of seats available in each IIT preparatory course varies significantly. Some courses may have only a few seats reserved for the ST category.
* Cutoff ranks: The cutoff ranks for admission change each year based on the number of applicants and their performance. A rank of 392 might be well above the cutoff for some courses but below the cutoff for others.
* Specific course choices: Your choice of course also matters greatly. More popular and prestigious courses will have higher cutoff ranks.
* IIT location: The IIT location might influence the cutoff, as some may be more popular than others.
In short: While your rank is excellent, you cannot guarantee admission without knowing the specific cutoff ranks for the courses you've applied to. You need to check the official admission lists released by the respective IITs after the admission process concludes to know your status.