Truck acked like dead battery changed both then drove 8 to 10 miles and it did not start again then changed alternator then again it seems to have a dead battery and will not start what do I look at next
This is a 350 ford power stroke turbo

If you can, remove and charge each battery. When I installed a new DieHard Gold battery in my 2000 Taurus five months ago, I had to charge it for 3.5 hours first. Diesels require very strong batteries, so I'd recommend that you also charge them. Check the regulated battery voltage with a multimeter:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1973613

This link may also help, if you suspect the starter motor is the culprit:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235560