Evans and Evans does not give the names of the musicians, but writes,
"May 15, 1929 - New York, Columbia Records.
Mason-Dixon Orchestra (Frank Trumbauer Orchestra). Bix did not appear on this or any subsequent recording session. This is the first Trumbauer recording session without Bix, and the first recording for Columbia records as a result of the May 19, 1928 contract."
Evans and Kiner give information about the May 19, 1928 contract. "Trumbauer saw Tommy Rockwell at Okeh records and decided upon a contract that called for eight man for Okeh and and eleven for Columbia."
I looked up the discographies for Trumbauer in Evans and Kiner for 1928-1929
20 Jan 1928 From Monday On/Mississippi Mud 11 men
3 Apr 1928 Our Bungalow/Lila 10 men
10 Apr 1928 Borneo/My Pet 10 men
5 Jul 1928 Bless You Sister/Dusky Stevedore 9 en (this was recorded in Chicago)
20 Sep 1928 Take Your Tomorrow/Love Affairs/Sentimental Baby 8 men
5 Oct 1928 The Love Nest/The Japanese Sandman/High on a Hilltop/Sentimental Baby 9 men
8 Mar 1929 Futuristic Rhythm/Raisin' the Roof 11 men.
17 Apr 1929 Louise/Wait till You See 'Ma Cherie'Baby Won't You Please Come Home 11 men
30 Apr 1929 No One Can Take Your Place/I Like That 14 men
15 May 1929 What A Day/Alabamy Snow 11 men. The 11 are
Margulis, Goldfield, Secrest t, c Rank tb Tram, Hazlett, Friedman reeds Hayton, Lang, Leibrook & Marsh rhythm
21 May 1929 Nobody But You/Got A Feeling for You 11 men
22 May 1929 Shivery Stomp/Reaching for Someone 11 men
18 Sep, 1929; 10 Oct 1929; 15 Oct 1929 11 or 13 men
So the contract that called for 8 men in OK records and 11 in Columbia was not followed strictly -before or after May 19, 1928 All the above sessions except for May 15, 1929 are OK; May 15, 1929 is a Columbia session.
I gave the above data for the sake of completeness, not because it provides insights.
An old discography - Delaunay 1948 gives for the Mason Dixon session
Are there two or three trumpets in the Mason Dixon recordings? I think two, but I am no good a recognizing the number of instuments in ensemble work. I don't hear a violin. Ray Mitchell does not list this session in Lang's discography. The Mosaic set on Bix and Tram and Teagarden gives
Secrest, Margulis c, t Rank tb Tram, Hazlett, Friedman reeds Hayton, Lang##, Leibrook & Marsh rhythm ##Lang on What A Day, unknown in Alabamy Snow - Mike Peters gives possibly Snoozer Quinn as unknown