6.2 or 6.5 chevy diesel....are they worth it???

[americanmusc1e]

I like my truck as a daily driver. I don't tow with it and I don't need to race it. Right now I have a 383 and a 700r4 and I get around 10mpg when the 700r4 is not in the shop getting rebuilt (I've had 2 major rebuilds by 2 different transmission guys -that's $3000 in transmissions- and and its been in the shop constantly)

I'm considering a weekend toy to put the 383 in and I would like to put something in my truck that doesn't cost too much and gets decent mileage.

A 6.2 (or a 92-93 manual Injection pump 6.5) Chevy (detroit diesel) and a NV4500 manual transmission would be a pretty easy swap and I should get around 20mpg. I can also find running trucks on craigslist for less than $3000.

question is.......I have heard alot of bad things about these motors......what are the main problems and how bad are they???