(Lazy alert - the car is in storage!)

Looking at investing in one of these ... but I need to know the steering column shaft size. Would anyone happen to know which size I need? My Indy uses the Sierra column I believe.

Thanks!

https://www.bg-racing.co.uk/quick-release-system-weld-on-6-point-shaft

You select what shaft size you want when you buy it, the sizes are also listed on the details section 5/8 3/4 or 1"