So im basically starting over on FM4, I had soooooo much then had a child and sold my old 360 slim. So I just got another 360 and recovered my gamertag. Im able to download some content in car pack but not all of what i use to have a few years ago. Which was just about everything, anyway to get this back or is it gone and i have to pay again? Doubt ill pay again.
All purchased content on your GT will be under Download History - link to help find it
Not all DLC will necessarily show in your Download History. Forza is funny that way.
I recommend going through the steps provided in the link below to perform a License Transfer to get everything you previously purchased available on your new system.