When I order something from a catalog or eBay, I think a reasonable time frame in which to recieve the item is 7 to 10 buisness days.
If the salesman told you your order would be shipped Monday, he obviously was wrong, since we've leared from another post that Chevy Dutys regular shipping day is Tuesday.. maybe the guy meant the first part of the week? Maybe the guy was new.. who knows.
Most packages sent within the continental U.S. via UPS ground arrive within 3 to 5 WEEKDAYS (saturdays and sundays don't count since they don't deliver ground packages those days)
From all the problems i've read about Chevy Duty on this board, you should consider yourself lucky that the part they actually sent you wasn't a fuel pump for a '76 Chrysler Cordoba.. cause when you called to complain that you recieved the wrong part they'd just tell you it was your own darn fault for ordering the wrong thing.
Good help with autoparts stores is hit and miss regardless of where you go, and it gets even further complicated when you're doing the deal long distance.