  Pulsars associated with supernova remnants (SNRs) are valuable because they
provide constraints on the mechanism(s) of pulsar spin-down. Here we discuss
two SNR/pulsar associations in which the SNR age is much greater than the age
of the pulsar obtained by assuming pure magnetic dipole radiation (MDR)
spin-down. The PSR B1757-24/SNR G5.4-1.2 association has a minimum age of ~40
kyr from proper motion upper limits, yet the MDR timing age of the pulsar is
only 16 kyr, and the newly discovered pulsar PSR J1846-0258 in the >2 kyr old
SNR Kes 75 has an MDR timing age of just 0.7 kyr. These and other pulsar/SNR
age discrepancies imply that the pulsar spin-down torque is not due to pure
MDR, and we discuss a model for the spin-down of the pulsars similar to the
ones recently proposed to explain the spin-down of soft gamma-ray repeaters and
anomalous x-ray pulsars.
