The Five Types of Budd RDC

1. RDC-1 - All-passenger configuration with control vestibules at each end.
2. RDC-2 - Mostly passenger with a small baggage compartment at one end.
3. RDC-3 - Half-passenger, half Baggage/Rolling Post Office.
4. RDC-4 - No passenger, half baggage/half RPO (only 73ft long)
5. RDC-9 - Powered Center Car - no control vestibules, only usable as middle car with other RDCs.

Budd RDC-1 - All-passenger

This is Budd RDC-1 ORRX-10 (formerly BCRail #BC-10) at Astoria Depot, Astoria OR on Friday 9th July 2004 during a layover on the Lewis And Clark Explorer service operated by the Portland and Western Railroad on behalf of the Oregon Department of Transport.

Budd RDC-2 - passenger with baggage compartment

This is Budd RDC-2 #712 of the Alaska Railroad at Hurricane AK on Thursday 20th May 2004 during a layover on the first southbound Hurricane Turn service of the 2004 Summer Season timetable.

Budd RDC-3 - Half-passenger, Half Baggage/RPO

This is Budd RDC-3 ORRX-31 (formerly BCRail #BC-31, nee-Great Northern GN #2350) at Astoria Depot, Astoria OR on Friday 9th July 2004 during a layover on the Lewis And Clark Explorer service operated by the Portland and Western Railroad on behalf of the Oregon Department of Transport.

Budd RDC-4 - Baggage/RPO

Only one RDC-4 is believed to remain operational; this is VIA rail Canada's #6250 which is a regular unit on their "The Lake Superior" service. Click to enlarge.

Source: Canadian National RR RDC-4 #6450 on Train #639-#640 at Niagara Falls, ONT on April 3, 1970   Author: Roger Puta via Marty Bernard.

From Wikimedia Commons, the free media repository

Budd RDC-9 - Centre Coach

RDC-9 at Tigard, Oregon. John Boone photo June 2020. Click to enlarge.