Just do the usual once over and find a truck that is stone stock and unmolested. If you see anything with the hardcore tuner boxes and other fun stuff, she's had a hard life. Better you do the mods and know YOU beat her up than having to find out the hard way from someone else's abuse.
You already know about the transmission issues and how weak they are, even at stock hp levels. Do yourself a favor and budget for trans upgrades; you won't regret it. If there are any TSBs on the truck or recalls, harass Dodge and get them fixed. I think the CRDs had some issues early on, so it doesn't hurt to check.
Once you find a truck you like, get a sample of the motor oil and trans fluid for analysis and base the purchase on what you find out. If they get all uncomfortable about the request, you know what's up. If it passes, go get her.
