  Let X be a smooth projective curve of genus g over a finite field F_q of
characteristic p. Consider primes l different from p. We formulate some
questions related to a well known counting formula of Drinfeld.
  Drinfeld counts rank 2, irreducible l-adic sheaves on the base change X_n of
X to F_{q^n} as n varies. We would like to count rank 2, irreducible mod l
sheaves on X_n as n varies. Drinfeld's l-adic count gives an upper bound for
the mod l count. We conjecture that Drinfeld's count is the correct asymptotic
for the count of rank 2, irreducible mod l sheaves on X_n as n varies with
(n,\ell)=1.
