[nradov]

Military vehicles had much more in common with their civilian counterparts in the WWII era. Technologies have almost entirely diverged since then. An M4 Sherman tank had a gasoline piston engine and steel armor. An M1 Abrams tank has a turbine engine, and uranium and ceramic composite armor. To convert a factory from one to the other you'll have to rip out almost everything and start over.

[toss1]

Yes, mil tech has diverged, and much of modern manufacturing requires highly specialized tooling that requires long lead times to get into production.

That is an excellent reason to subsidize maintaining convertible or dual-use tech in the civilian arena. e.g., make sure turbines are used in more civilian uses. Stockpile tech that is really civilian incompatible such as the depleted uranium armor.

Turbines are a good example of how a civilian tech could have gone differently. In the 1960s several turbine-powered cars were in development for street use and a turbine race car qualified and lead most of the 1967 Indianapolis 500 race. But then the USAC effectively disqualified it [0], and civilian development stopped for other reasons. But it arguably might have continued had turbine power been allowed to race and dominate.

Yet, turbines are used both for aircraft and for natural gas power, both stationary and portable, and there are many small turbines. So, of course, we would not go to an ICE engine builder but to the builders of aircraft and gas power plants. There are also manufacturers of small-scale turbines that might ramp up.

On the other hand, we can also look at how modern warfare has changed over the last three years. multi-million dollar tanks are being reliably destroyed by $800 drones. And drone tech is highly fungible. Many common computer chips and boards can be used to control it, many common lightweight motors will work, and composites or lightweight metals can make the bodies. All of these technologies are highly configurable, so it would be a short lead time to make new factories to turn out pretty much whatever shape drone we wanted, whether it is flying, rolling, or swimming.

[0] https://en.wikipedia.org/wiki/STP-Paxton_Turbocar

[nradov]

There was never any possibility of turbine engines becoming widely used for civilian street autos. They are less fuel efficient and have slower throttle response compared to reciprocating internal combustion engines. This is inherent in the technology, not something that could have been fixed with further development.