what transmission should I get to replace mine in 2004 f 150 heritage

You could have it diagnosed and repaired at a transmission shop. It's very possible they can rebuild yours and save your self some money. It's also possible it's not the entire transmission that's bad. Use this link to find a good shop near you. https://repairpal.com/repair-shops Alex

This transmission is likely a 4R75W. But as Alex said, inquire about options. What constitutes a "blown transmission" -- these transmissions are not really known for catastrophic failure unless you've used the vehicle for something it was not intended for. If you take your VIN to a Ford dealership, they can look up the build of the vehicle and tell you the exact transmission model used, as an alternative.