It's hard to find but here's the numbers.
Ford is clearly numero uno in diesel sales, generic motors, when you combine cheby and gmc, are a close number 2 and Ram is last. By a goodly margin
Make of it what you will but, IMHO, it's the new transmission that is the deciding factor. or not
YMMV
https://www.dieselforum.org/vehiclesales/u-s-vehicle-sales-dashboard#:~:text=Sales of commercial diesels represented,percent of total vehicle sales.
Diesel technology forum is generally a pretty thorough site but they are listing vehicles that haven't even been sold in the US since 2015. Very odd...