Which of my ribbons from the Marine Corps can I wear in my Army uniforms? And what Army specific ribbons do I add?

I don't know what a GCD is but you'll wear the NDR and GWOT on your left side and your MUC on your right. You'll also add an Army Service Ribbon on your left.
The Army let's you wear almost anything from a federal service. My old CO wore his SEAL Trident and I met USN and AF people who wore their badges as well.

Check out AR 600-8-22

Ref 1-37 in 600-8-22. The following came from the HRC Awards site:

Soldiers awarded a decoration or badge for service with a Sister service prior to service in the Army need to request wear of that decoration or badge to HRC ADB.

To request to wear Sister service awards, a Soldier must submit a memorandum or DA Form 4187 requesting wear, documentation showing the requirements for the award and certificate and/or citation confirming the requirements were met, and appropriate orders or other official supporting documentation that clearly defines the assignment relationship to the other service to the HRC ADB. If not clearly documented, the recommendation will not be approved for acceptance or wear.

Effective 2 August 1990, a commissioned officer of the U.S. Public Health Service (USPHS) assigned or attached for full-time duty to the DOD or any of its components is eligible for military awards and decorations on the same basis as officers of the military services. However, no military ribbon, medal, or decoration will be awarded to an officer of the USPHS without the approval of the Secretary of Health and Human Services or designee. Requests for concurrence may be obtained from USPHS Commissioned Corps Liaison Office, Office of the Assistant Secretary of Defense (Health Affairs), 1200 Defense Pentagon, Room 3E1070, Washington, DC 20301–1200.

https://www.hrc.army.mil/content/Sister%20Service%20Awards

All USMC awards can be worn snd all Army awards you now rate.

All of them. You can add the Army Service Ribbon when you get MOS qualified in the Army.

Been awhile but when I cross decked from the Army to USMC. The day before graduation my Seinor went down looked in my record book, found out what I rated and brought it back to me. It amounted to 1GC, 1OSR (kinda like our sea service) 2AAMS ( Like Navy Acheivment medal)that got out of Korea. No Asr, no ANOC, BNOC (Those are leadership schools) and no anything else. But u should be fine They get GWOT and ND out of basic. You can wear both conducts, bc the Army awards hashmark every 3. But yea submit the paperwork. You'll be surprised what you can keep.