On page 8 of my copy of "Raise High the Roof Beam, Carpenters" Buddy tells us that he is pretty exclusively concerned with Seymour's story. This probably shouldn't be a shock as the book also includes, "Seymour An Introduction" but Buddy adds that Seymour was in the Air Force (then still the Air Corps) and that he was probably (emphasis Salinger's) the "acting company clerk." [Incidentally, this detail has some ambiguity as the Air Corps itself began to serve under the Army Air Forces in 1941.]
We also learn that he was not a prolific letter writer. Since later in the novella, Seymour's diary is such an important part of the story, I find this an odd contradiction.
Buddy says he hasn't had more than five letters from Seymour in his whole life, and he is speaking AFTER Seymour's death.
In fact the narrative time of the novella is 1955 after Seymour's suicide and the completion of the war. Unfortunately, this detail is omitted from the Glass Family Chronology
...to be continued...