V10s are very hard to find used, and of course that is the only option to find one anymore. First off, I hope you want a Crew Cab Short Bed, because that is probably 70-75% of the production run, best I can tell. I think V10s were probably less than 10% and maybe even less than 5% of production (my own WAG). If you want a diesel CC SB you will have plenty to choose from, but you are in the same type situation I was. I don't drive it a ton, so I wanted to stay away from the diesel as people seem to say modern diesels have "issues" when they sit around too much - more so than gas engines. Since I really wanted an Ext Cab LB, I took the first decent gas engine I could find in that configuration (pretty rare combo), and mine was the V8. It's no diesel or V10 for sure, but it gets the job done just fine for me. It might work for you too, depending on what your needs are. Something to keep in mind, and at least look into/try out if the right vehicle pops up. Never read a bad word about the V10s other than they suck gas. One of the best kept secrets out there in 3/4-1 ton trucks, it seems.
Only common issues to watch for are the early 05's had a transmission issue (mine was one, and was repaired under warranty by the PO) where the case can crack due to a design issue with one of the internal retaining rings. They changed the design pretty early on when they caught it. The other one is the sticking plugs in the V8&10. They also did a design change on that at some point, but I'm not sure when. Maybe 06 or 07. So if you can find an 07 or 08, you should avoid the only real known issues for sure.
Good luck. It took me close to 6 mos to find one that fit my needs in this area (near Minneapolis St Paul Metro)