Not to be argumenative, cause I really am not sure, but I thought it was an LOA.
I'm about 90% sure I have no idea though.....
LOAs are not type ratings. Although they are similar, there are some differences.
First off, once you have an LOA in three different aircraft, you get an "unlimited LOA" which is good for almost anything.
Also, most of the "examinaiton" for an LOA in a some fighters (the P-51 for example) is done in an entirely different airplane usually a T-6 Texan. And it focuses on VFR manuvers and basic airmanship.
Basicly a type is a examinaiton of your knowledge of an airplane, and you ability to fly it IFR. This should not be beyond any compentent pilot who has recived sufficent training.
LOAs OTOH, are there to see if you can really handle this extreamly challanging airplane, and many pilots simply are not up to the task.