Old Ford Diesel Question, Need Help.

[Truckie]

Here is a question I don't know what else to tell my neighbor to do with his old Ford. Its a 1986 with the V 8 diesel and he is having troubles with it, heres whats happening. Ones you start it you cant shout it off or you may never get it to start again till it sits for a few hours, and some times it will start after shout off but it cranks for bout 30 seconds before it fire up. He took it to the local garage and had new glow plugs installed, had a short in the wiring fixed, new fuel lines and several new fuel filters. After all that it worked fine for a few days and then started to act up again. He took it to the Ford dealer and they checked the work and said it was OK, but said the problem in he had dead batteries so he replaced them and it worked for a while again and now it is acting up again. I don't know what else to tell him other than to buy a CTD:-laf :-laf and all his problems will be over with, but he wont do that so any help is greatly appreciated as he uses this truck for his daily work truck and may not get shut off and run up to 12 hours at a time. It is a 1 ton with a steak body on it

Thanks for any help.

MIKE