Looking for a better looking set of gauges and found some 550s on CL I know quite a bit is interchangeable but the gauges between the two have different readings. My 73 500 only reads out to 120 and the 550 reads out to 140. The tach looks similar, redlined in the same range but mine has a 12k mark and the 550 goes to maybe 11.5k which both are well beyond the redline area. I beleive the 550 is a 76 or 78. Attached is the photo of the 550
