I am buying diesels only for last 20 years and the only reason wife drive gasoline wagon is becouse last good diesel wagon sold in this country about year 1990.
I drove VW diesel wagon for couple of years but DW hated that thing.
Coming to Ford diesel, the 7.3l is very reliable engine but comparing to newer it sucks fuel and suck in power, but your wife will know you are coming when you are 3 blocks away.
I bought 6l, but as already mentioned that is troublesome engine. I am mechanically inclined and drive carefully observing the gauges.
Still when empty my dually is regularly beating BMWs between the lights.
Bought the truck cheap enough to play with it, but would never recommend it to someone who is not expert on diesels.
If you can afford, go for newer engines. I am drooling when I see quiet 450 HP diesels and sure one is on my list once I hit the lottery.