Hey, what is the redline on a turbo vs the NA engine....I have 2 of the small tachometers and the redlines are different. I also have 2 of the Turbo gauges and the colored sweeps are different, is one for an intercooled model?..just asking...Thanks

Small tachs mostly appeared in 240 GLT and GT models. I'm guessing the small tach with the higher red line is possibly from an early 240 GLT with a B23E engine and the lower one possibly from a later GT turbo. Could also be block differences like B21F/FT vs. B230F/FT. Peak rpms are notably different. Reference this old post here regarding large tach differences https://www.brickboard.com/RWD/volvo/319267/220/240/260/280/re_stock_redline_b230f.html

Other red line differences could for the various 2.0 litre blocks used in Europe.

Do a Volvo parts lookup using the p/n's off the back then check the fitments listed for it. Some of the fitments may not be as engine specific as you'd like, but if you come at them a number of ways such as which engines were available in which years or doing p/n lookups on different sites (like Skandix) then you can usually figure it out.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Are you sure about what your extra tach came from? Tachs made for the 260 series (V6 motor) have a redline of 5500 rpm. As far as I remember all the red blocks have a 6000 rpm redline. Some tachs are clearly marked on the rear cover--4 zyl-- or 6 zyl. - Dave