  The complete spin structure of the pion-nucleon-loop contribution to the
delta self-energy and dressed propagator is calculated in vacuum, with the most
general form of the pion-nucleon-delta vertex. The imaginary parts of the ten
Lorentz-scalar coefficients are calculated in closed form, while the real parts
are obtained numerically from a dispersion relation. The effect of the
pion-nucleon-delta coupling constants and form-factor on the pion-nucleon
phase-shift in the spin-3/2 isospin-3/2 channel is studied.
