Note the space between the 7 and the t on the last line. The default operation in MS Word is to superscript the th on the first two lines, and leave it normal font on the third line.
The forged document had the same three instances in the document, naming Bush's Fighter Interceptor Wing. Two were superscripted, while the third wasn't. There is no typewriter in existence at the time the document was written that could replicate that.
Some zealots are claiming the IBM Selectric could. It would require replacing the ball, and manually moving the roll to type the 'th' between lines. It is not possible to do that and get the precise spacing between the lines. Anyone who might attempt that would not leave the third instance normal.