First of all I am not in any ways an expert, but since no one has yet responded to your urgent cry for help, I will give it a shot.
1. Find the seriel number for your tractor. This is a unique code which will carry all the info. There is a area here in this site which will tell you the year and model # etc. and how to find it.
2. How do you know you need a new head? If you do, there should be a tractor company near you which is a good place to start. Since this is still a fairly 'new' old tractor, my guess is that you will be able to find on very easily