A Body Aftermarket Tach Size

My dad installed an older Sunpro Super Tach II (probably 20 years ago) in the Rallye Cluster on my grandfather's 71 Twister when the original Tach died.

As far as I know he didn't have to butcher the cluster to fit it in (I believe he removed the entire tach from its aftermarket housing and mounted it in the cluster without the housing). A quick look online shows the Smaller Super Tach II is still available too. http://www.summitracing.com/parts/sun-cp7906/overview/

The one in my grandfather's Twister has a different face, but that's not surprising since I imagine they've changed the look a little bit after 20+ years :D