Internal or External Water Pump?

[aukaiiki]

Aloha,

I'm restoring my 83.5 Westy and it came without the watertank. I got a tank from a newer Westy but without the pump. How do you tell if the tank had an internal or external pump? And will it matter what pump I use?

Progress:

I removed all the remains of the cabinets and found a rust area between the inner and outer driver rear fender plus the passenger nut that holds the rock & roll bed is rusted out. The plans are to replace these two areas with new panels.

Mahalo Nui Loa and Mele Kalikimaka,
aukaiiki sends...