16 Sr (11 first or co-first string)
11 Jr (8 first or co-first string)
14 So (6 first or co-first string)
7 Fr (3 first or co-first string)
That's counting individual players, not spots (so Algie Brown is not counted twice, even though he is in two spots).
Positions with no seniors on the two-deep: RB, SLOT, WR1 (X receiver), LT, C, RG, LE, NT (that makes the whole D-line, until Marques gets back), RE, BLB, KAT