Forgive this rather dumb question...

I'm looking at purchasing a dial gage. Problem is, I've never used one and I have no idea what exactly I should buy.

Looking at the pictures it looks like I would need some way to mount the gage so it remains stationary.

If you were in the market for a dial gage. Specifically to test chain stretch and you didn't want to spend a fortune, where would you look? What would you get?

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'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.