how do i go about hooking up a new tach on my 95 12 valve? can i do it with out the computer?

 

No, but you can buy one of these, work excellent.
http://www.tinytach.com/tinytach/diesel.php

 

how are these guys putting these big tachs in their trucks? how are they hooking them up? i want one that will read more than the factory tach.

 

You can get tachs that pickup off of balancer, similar to how the stock 12v does it, but they usually have 4 notches instead of the 2 that our trucks have.

 

the autometer diesel tach is nice and goes to 5000 rpms, i got one from summit. hooks up to your alternator very simply. you do have to calibrate it though. A buddy with one of those snap-on portable tachs works well for that if can find one.