I fused mine with a 5 amp fuse just in case, Also if your going from a 4cyl to a 6cyl, or 6 to 4 your rpms will be off, there is a white potentiometer on the upper right corner of the tach circuitry you can adjust the gauge with. You have to do this while it is installed with the plastic cover off, but luckily you can get it right while the cluster is bolted in and then snap the crystal on without taking the cluster back out, just watch the little plastic idiot light covers on the botttom and don't let them fall off before the clear cover goes on, the you have to take it all out again. Don''t ask how many times I did that... Ok, at least 8 times...sigh, at least but not for the same reason, once I forgot to hook up the spedo cable, and realized it after the whole dash was together....sad I know.

If yours is a cable type, unhook the cable on the firewall under hood, and poush it foward after cluster is unhooked. Much easier!