What constitutes being "old school" in the military?

For each current generation... it is usually the generation that’s a couple generations before the current one..

MRE's I guess I was really really old school! M-14's and C Rations. I would do it all over again.

Active Duty
19 AUG 1983 - 20 SEP 1987
Reserves
20 SEP1987 - 1 MAR 2008
Old school to new school

Being issued Green combat boots, understanding that mission accomplishment comes before troop welfare for the board answer, but seeking good balance in reality. Never letting anyone senior to you outdo you in PT. Knowing the systems involved in your service and being able to manage them to accomplish what you need in a timely fashion. Knowing each individual in your unit and how to best apply each person to get a job done. That is just my two cents though.

Remember them all, good times, D51

I was in 1998-2006. I'm not as "old school" as some but I do remember:

Polishing and spit shining black boots.
Woodland camo BDU's were the issue uniform.
Grey PT shorts and T-Shirts.
Buffer "rodeos" in the squad bay while paste waxing the floors.
Being issued a shelter half to be used with your battle buddy who had the other half.
Using Brassiere to polish the trash can and the shower drains.
Being issued an M16A1 at my reserve unit until we got A2's.

You forgot using a P38. If you can find your equipment from your platoon in a Museum.

It's whatever the longest serving guy you are with says it is because it all got easier after that and the last group that had difficult standards was his. Just cause he served with LTC Custer at the Little Bighorn doesn't make him a Cavalry expert :)

We called them big bird PT suits. Add peeling your frozen to the ground sleeping mat, or patching your leaking air mattress.

As long as he or she is junior to you: The day after they came in...