So I put some thought into this and wanted to make some era accurate images, as if they came from an alternate past. I focused on the robots, since they're always fascinating to generate.
I usually like to keep my submissions (like my attitude) light and positive. But these got quite dark from the moment I started to generate photographs.

Description: 1920's. Robots are seen as a novelty, inventors show off the nimbleness and sophistication of their designs. This oil painting depicts a demonstration of a ballet-dancing automaton in a fancy music hall.
Prompt: oil painting, dieselpunk style, a ballerina dances in a ballet together with an automaton, the automaton is slender and elegant, in a music hall, 1930s

Description: 1930's. Robots are no longer a novelty but are being mass produced in huge factories. This photograph shows an almost finished land crawler. Factory workers are putting the finishing touches on it's chassis.
Prompt: 1930s monochrome photograph, dieselpunk style, a gigantic land crawler is being assembled in a factory assembly line, workers wear gas masks, the air is thick with smoke, industrial, realistic, iso 800

Description: 1940's. Of course mankind eventually finds a way to turn anything into a weapon of war. Robots are used to cause terror and destruction in the many wars that ravage the continent.
Prompt: dieselpunk style, 1940s photograph, warzone, a giant army robot approaches a ruined building

This is fun, all of these were done with Midjourney, aspect ratio of 16:9, prompts at bottom

Prompts were

• dieselpunk, a diesel engine spider attached to an enormous industrial building of another, in the style of meticulous military scenes, otherworldly design, muted earth tones, manticore, 8k, emphasis on detail
• Dieselpunk, an illustration of the main character of the game, dieselpunk soldier, intricate gas mask, in the style of light brown and dust, ivan albright, ps1 graphics, soldier art, intense action scenes, kevin hill, animated mosaics, pollution
• dieselpunk, an illustration of the diesel airship from the game, blimp, in the style of light brown and dust, ivan albright, ps1 graphics, soldier art, intense action scenes, kevin hill, animated mosaics, pollution

I'm a bit late, but here are my submissions, all made with Stable Diffusion.

Dieselpunk Terminator Mk.I

Dieselpunk Terminator Mk.II

Dieselpunk Lunar Base

eco mode on

eco mode off

eco mode off

These are very large (3000x2000), so here's an album link: https://imgur.com/a/LOZcR39

Love at first sight.

Obligatory gas masks and fire.

What the fuck does anything on this vehicle do?

Midjourney prompt: ((scared villagers running away)) from a giant (steampunk) robot towering over a cluttered cobblestone street, running towards the camera, dieselpunk style, sketch, warzone, many pipes and cables, billowing black smoke, rusty, rain, dreary, wet, mist, extreme detail --upbeta --s 250

Less Diesel-Punk-y, but my daughter and I liked the picture more because of the feel of it... LOL

Here's my submission, I just typed "dieselpunk", "dieselpunk city", and "dieselpunk plane" into DALL-E2 image creator.

~~Also testing to see if imgur albums will fully display in a single embed~~ (imgur album doesn't show up embed in comment, have to do 1 image at a time)

I wanted to mix dieselpunk and nature. I installed Stable Diffusion two days ago and I am quite happy of my progression. I don't have a GPU so it takes forever! Here is my batch.

The defiant artist

After the machines had taken over every work of art had to be in the style the machines approved of. This defiant artist will be deported for reeducation and just learned that her family will be joining her.

Path to glory

Elite machine totenkopf troops on their way to eliminate the last human army.

gym girls walking down the lively street, DieselPunk

a dozen shirtless workers working in industrial zone, DieselPunk

A lot going on here. … I know it’s AI but my mechanical brain is still looking at the image and trying to make imaginations work. We have what amounts to a “pony” motor above the real motor, and a high rise intake manifold behind the pony motor, but then we have exhaust manifolds from the pony motor heating up the ‘real’ motor and one hell of a coal roller for the real motor. Oh it’s a deuterium 256 motor. That explains it.

crAIyon, photo style - various prompts: