I'd like to install a vacuum guage in the cab so i can monitor the engines performance. I've never shopped for one before, so I'd like to know what you guys would suggest. I'd prefer mechanical, not an electrical guage. Size isn't a big issue, more readability is my concern. I'd probably mount it on the door jamb at eye level for quick reference. Accuracy is probably the most important. Are some makes of guage more reliable than others? thanks