Jay74, Misty71:
I think Eastwood just has a core group of supporting actors with whom he feels comfortable.
Bradford Dillman ("Captain McKay" in "THE ENFORCER", "Captain Briggs" in "SUDDEN IMPACT"), is but one example.
Another is Michael Currie, who played "Captain Seerbacker" in "FIREFOX" (1982), "Lieutenant Donnelly" in "SUDDEN IMPACT" (1983), and "Captain Donnelly" (presumably the same character following a promotion) in "THE DEAD POOL" (1986).
Still another is Gregory Walcott, who played "Bob Mitchell" (the Sinola County Sheriff) in "JOE KIDD" (1972), and "Pope" (the overconfident CII operative) in "THE EIGER SANCTION" (1976).
And let's not forget the late John Mitchum, who played "Inspector Frank DiGeorgio" in "DIRTY HARRY" (1971), "MAGNUM FORCE" (1973), and "THE ENFORCER" (1976), as well as "Al" in "THE OUTLAW JOSEY WALES" (1976).
--John