I made a number of vectors (plasmid and cosmid) that have one
XbaI site and two PacI sites. They were not constructed for
cloning in these sites, but can be used for it if necessary.
They are named pEEC3 (stands for Extremely Elegant Cloning)
and Tropist 1, 2, 3 and 4. They are described in Gene, 136,
215-219 (1993). I am heppy to send you some DNA if you need