What constitutes being "old school" in the military?

That depends .... When I went through Parris Island in 1965, I lived in the old wooden WWII barracks. Those barracks have been replaced by brick barracks. At ITR we rode in "Cattle Cars" and lived in Quonset Huts. Plus, I qualified with an M-14 not its replacement. In Vietnam we ate C-Rats or a Field Mess, and I have never had an MRE. Therefore, I say I am "Old School".
Semper Fi - Oooorah

Duplicate here..Old school if you accidentally hit the post button on the new fangled phone lol
C rats per previous
First rifle said XM 16 E1 made by GM Hydromatic division
You know what a "pickle suit" is..
First jump in Division included a pink steel pot and a CEWI bag
You know what a steel pot is
You know that a CEWI bag is pronounced "weecee bag"
You remember what STRAC means
5 event PT test
Pulling CQ

Use a toilet seat cover for a floor buffet pad
Had a drill Sgt yell toe to heel, make your buddy smile
Kept hard liquor and beer in your quarters
Had a beer vending machine in the barracks
Seeing a sweaty, dirty, female Trainee was highlight of your week
Going to the nco club drinking and playing the slots
Learning xrated cadence songs from your platoon Sgt
Having a phone call or letter be your only link home.
NOT wearing a silly beret

I knew a guy...
Thought he was old school, after being in for 6 months. I laughed him out of the building.
You're old-school, when everyone around you starts calling you " old school".
Until then, who cares?

My last six months of service was in Honduras and we had a pallet of C-rats for chow, as the cooks in the distant HQ unit would never serve anything out of their hours. We drank from a water buffalo that we liberated, shaved from our steel pots, built our own shower and two holer. The first MRE I saw was handed to me on the C130 leaving for home, and I wondered "What the hell is this, and why are they giving us Styrofoam to eat?"

If you carried and ate C-Rats you opened with a John Wayne you carried on your dog tags.

Well my PT shorts were red cotton. Yellow USMC shirt though. C-Rats with the cigarettes as someone as mentioned. After boot camp on to Camp Pendleton for "ITR" (Infantry Training Regiment) where I was issued and used an M1 during the training.

I was a L/CPL when the PRT changed to the PFT. Away with boots, utilities, cartridge belt w/canteen, steel pots and sometimes even a rifle doing the 3 mile run in formation. Away with the jump and reach, mountain-climbers, pushups, stair-steps.... to PT shorts, Yellow T-Shirt, tennis shoes!!. 3 mile run, sit-ups, pull-ups. Run time from 36 minutes to 28 minutes.

We were always told that the 3 mile run was to make sure we could run 3 miles in combat and be able to fight when we got to where we were headed. Even us "Snuffies" at the time realized that we're not going to run in combat in read shorts and tennis shoes. Of course testing our overall cardio capability just didn't figure for us.

I remember washing up out of my steel pot and laying my M1 and later M14 in the dirt next to me. Never gave malfunctions a thought.

Remember on Okinawa watching a handful of old WWII veterans attending a morning colors event in 1986. They were about 41 years away from their war in the Pacific on Okinawa. They were truly "Old-Corps". I respected them and their ways.

Now, along with friends I'm 50+ years out of my war in Vietnam. I wonder how we're looked at my the current Marines.

and yes... I'd do it all over again.

If you know term. Be On Time, Be In The Right Uniform and Do As Your Told!

You drank from one of these, while eating C-rats.

Had coffee can hung on the 4 x 4 posts in the 2 story barracks to be used as butt cans, had the water in those cans freeze over during the night, and wake up with a dusting of snow on your GI blanket. Walked fire guard to insure everyone was alerted if the coal fired furnace caught the building on fire. Jumped off the short roof between the first and second story into the snow drifts between the buildings. Wore khaki burmuda shorts with long gray or tan knee high stockings as a summer time class B uniform. Was issued brown boots and low quarters, and later dye kits to change their color to black. Wore "Overseas hats" with Khakis, ODs and later Greens. Had replaceable Khaki tops for the "truck driver caps" so you could clean and iron the one you took off. Went to the service club for a dance on Friday nights, with women from a girls club in town. Walked Guard Duty for 2 hours when your name came up on the roster.