that block has nothing to do with coolant
the previous owner probably tore out all the a/c componants at some point or another
the a/c condenser sits infront of the radiator (slightly smaller) and theres usually a can lookin deal (cant remember what its called at the moment) buy the radiator...
If you want brighter LEDs are the way to go
IIRC they are 194 bulbs, so get LED 194 replacements in whatever color you wish to add a lil personal flavor to it
Speaking of which, anyone know how many bulbs are in a M cluster? :D