Want to replace 85mph speedo on 1983 Spider.

[Alfa2k]

I want to replace the 85mph speedo with a 120mph. What year would work best and do I need to replace the tach also? Thanks

[Tifosi]

There's no need to change the tach unless you want to put in one that has better paint or something. (if you're already goes to 8k, then you aren't going to find one that reads higher)

It may depend on what year you're working with in regard to sundry lights in the gauge as currently yours has the heater fan indicator while older versions may have something different.

IIRC, any speedo head from series 2 on through an 85 will work. (the different final drive ratios are delt with in the transmission at the speedo drive gear, not at the speedo head)