  Calculations of the spectra of various even-even nuclei in the fp shell
($^{44}$Ti, $^{46}$Ti, $^{48}$Cr, and $^{50}$Cr) are performed with two sets of
two-body interaction matrix elements. The first set consists of the matrix
elements of the FPD6 interaction. The second set have the same T=1 two-body
matrix elements as the FPD6 interaction, but all the T=0 two-body matrix
elements are set equal to zero. Despite the drastic differences between the two
interactions, the spectra they yield are very similar and indeed it is
difficult to say which set gives a better fit to experiment. That the results
for the yrast spectra are insensitive to the presence or absence of T=0
two-body matrix elements is surprising because the only bound two nucleon
system has T=0, namely the deuteron. Also there is the general folklore that
T=0 matrix elements are responsible for nuclear collectivity. Electric
quadrupole transition rates are also examined. It is found that the
reintroduction of T=0 matrix elements leads to an enhancement of B(E2)'s for
lower spin transitions but in some cases for higher spin transitions one gets
another surprising result that there is a small suppression.
