The installation process for both of these is quite simple....First. The tacho....
there will be 4wires coming out of it....
One will be positive...hook this upto your "acc" or "on" wires coming out of the loom from underneath the steering column.
Next will be Earth/Ground, this simply gets screwed into a metal part of the car.
Then you have Ill/Light. Wire this upto your park lights, there should be a wire behind your fusebox. Test using a multimeter or a test light.
The tricky one is the tach wire....Coming off of the coil or distributor there will be a small wire running between the two. This wire is called the low tension lead and it so the distributor can tell the coil when to generate a spark. Add this wire onto the low tension lead. Now everything should be running perfectly. See, I told you it wasn't that hard.
I think the hardest part about installing LED washers is removing the old ones first!! Get them out and keep them! you may have to put them back in place later on.
Put the new washers in and screw the nut in place without crushing the wires. Now, there will be two wires coming out of them a red one and a black one. The black wire is Earth/Ground once again screw that to a metal part of the car
Your getting the hang of this. the other wire is the Positive wire. Link this upto your park lights. That way, when you switch your park lights, the LEDS come on as well. I would suggest installing a switch inside cabin to be able to switch them off as well. Just use a simple toggle switch, cut the positive wire and put one wire on one side of the switch and th other wire on the other side of the switch and your all done!
Don't forget to adjust the water nozzles, use a paperclip straightened out, insert in the nozzle a little way and then move it until it fires water where you want it:)
ALSO make sure you wire in a fuse anywhere that you take power from.
Now, give yourself a pat on the back and crack open a can of beer. You deserve it.