This is NOT complicated.

a) The value is about 1.4 ohms for a 12-volt (nominal) system.
b) 1.6 ohms is usually suggested for a 6-volt system (some older VWs and tractors). But that same 1.4 ohm device will work fine.
c) They carry A LOT of current, and so are usually ceramic devices with substantial connectors.
d) They may be purchased for as little as ~$5 + tax for a generic device that may fit to as much as $20 + tax for a name-brand device that will actually fit.
e) They are still stock items in most auto-supply stores and dealerships.

Peter Wieck
Melrose Park, PA