God of Money - Chapter 6:

Chen Shiping, a Qi training monk from the Foundation Establishment family, is struggling in the world of cultivating immortals

- Description from novelbuddy

He died on Earth with nothing—no legacy, no power, and no second chances... or so he thought.After getting hit by a truck, a disillusioned young man awakens in the body of a boy named Zane, in a war-torn fantasy world where nations clash over power, and magic is the law of survival. Gifted a mysterious book from parents he barely knew—and now lost forever—Zane accidentally awakens the Void System, a cold, cryptic force that offers power... at a price.In a world of monsters, systems, and bloodshed, Zane doesn’t get a choice.Survive, or vanish into nothing

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

I was reincarnated into the world of Academy City.Since things turned out this way, I decided to aim for a decent job and live a happy life.As long as I catch the villains who will become the Great Villain, there shouldn’t be any problems.“Greetings. I am Ahn Woo-jin, a second-year student and the 45th Disciplinary Committee Leader this year.”And so, I became the Disciplinary Committee Leader, leading the top-ranked enforcement squad.