what's a good affordable aftermarket tach and not a digital one either.

 

That depends. Do you have single fire or dual fire? You don't show your year.

I say this because I bought a $75 analog tach and followed the wiring instructions for single fire and the tach bounced around by 2,000 RPM jumps. I took it off immediately when I got home.

I gave it to a buddy with an old '78 dual fire and it works great.

I bought a Dakota Digital speedo/tach/everything else combo and couldn't be happier, but it was a price jump for sure.