Needing Heater tap advice??

[Gaddy]

The Empire van doesnt have a heater tap so I want to put one in!!
Only thing is Im not sure of the difference in the taps available,or
wether they need to be mounted to yhe inner gaurd or they are kept
in place just by the heater hose!!
This is one I got from Greg!!

Not sure why thes one offers a threeway option, yet it does have the bits to cap the side one off!!
Im thinkin this one is the correct one, but still not sure about the mounting of it..
Thanks..

Any pics of yous would help also..

Cheers.
Gaddy..