First time stupid questions

[Fred Garland]

Own a 2004 2500. Have a couple of questions. #1 Have purchased 2 Autometer gauges. Is the best place over the steering column or in the storage mid-dash? (Want to keep the handle on the A pillar). #2 How do I tell if my model is a 2004 or 2004. 5? #3 Is tapping the exhaust manifold for the pyrometer difficult? (Have changed fuel/oil filter myself) #4 Truck gets run once to twice a week after being a daily driver. Last 4 months has developed a rough idle only when cold. Something to worry about? Fred Garland