Be aware though that if you have a tach, the numbers on the 100 or 120 mph speedo might not match. I was having trouble with my tach and a different one came in a box of parts I got with the car so I swapped it out to see if it made a difference and it was a couple of days before I noticed the numbers were different.
Looks to me like the numbers on my second tach match the numbers on the 100 mph speedo in the top picture, it may mean that my second tach is from a '75 (I don't really know). That second pic above is really hard to see, but the numbers look like they match up to my speedo. Just sayin', you will want to take a good look at the numbers on the speedo if you have a tach (I am also going to assume that all Spyders came with tachs, but I've been known to make bad assumptions.