Most of the gauges in the factory dash are not worth the space they take up--in addition to a Scangauge, consider an Edge Insight CST, or a DashDaq, both are easier to read in my opinion.
And the one thing most important to your diesel is the Exhaust Gas Temperature, which I don't believe is available thru the OBDII diagnostics plug under the dash on the Excursions.
'05 36TK3 Mobile Suites
'10 F450 new to me
'09 F450 Lariat 4x4--died