First Gen Rangers came with 4cyl diesels, '83 to '87, there were a few in '88
Good read here on what they were: The Early Ford Ranger Diesel Engines
The turbo diesels wasn't bad, without the turbo you basically tolerated it because of MPG, lol.
Cummins 4bt engine has been a popular, and expensive, swap.
Google: Ford Ranger 4bt