Here is a K-Line K-4532 O Gauge Golden State Passenger Car Set [6].
Features:

Each passenger car 13.5″ long
Overhead StreamLighting Illumination
Fully Furnished Interiors
Metal Grab Rails
Needle Point Axles
Fast Angle Wheels
Operating Metal Couplers
Underside Detailing
Authentic Paint Schemes
Diaphrams
Can handle O-27 and up

Passenger Cars included:

K4532-4301 US Mail RPO, Southern Pacific
K4532-0427 Golden Harvest Diner, Rock Island
K4532-3368 Imperial Terrace Pullman, Pennsylvania
K4532-6015 Combine, Rock Island
K4532-0214 “Golden Moon” Vista Dome, Southern Pacific
K4532-0479 Golden Divan Observation End Car with flat rear, Rock Island

This item has been graded per TCA standards C-6: Very Good based on visual appearance. The wheels show signs of wear. The overall appearance of this item may be improved with a gentle and thorough cleaning. There are light nicks and scratches on the surface of this item. The instruction manual is not included. The original box is included. Please check the photos for a detailed look at this item. Overall condition is Very Good.

Condition: Very Good (C-6)
Operational Status: Functional
Original Box: Yes (P-6)

Manufacturer: K-Line
Model Number: K-4532
Road Name: **** Assorted Road Names

Scale/Era: O Modern
Model Type: Passenger Cars

The SKU for this item is 5973761.

Product Id: 11724305