If you are not running any power adder, I would not waste the $$ on the FP Gauge for now..
If you want 2, the WT and OP are it.!
If you mount them together, you can splice the power source line, the light dimmer line, and the ground line together, then connect them to a single source.
Then, each sending wire will go to it's respective place....
You will get an Oil sending unit that replaces the stock one near the oil filter, and connect the sending wire to IT.
You will get a water temp sending unit that will either replace the stock one in the lower intake just to the right of the distributor, OR you can get an after market water neck that has a screwhole in the top to install a sending unit.
Since the one in the intake is more accurate, I installed the Autometer one in the intake, and move the stock one to the top of the waterneck in the screwhole provided, just to have both working..
Ill find a couple of pics to post for you.
RC