Daft question about gear selection

Being a new s3 owner I have a daft question about the correct use of the gear selectors. I'm not totally baffled about gears (having been hgv driver for 17yrs) but these knobs in the landy got me stumped.
Apart from the gearstick, I have a red selector, a yellow selector and a black selector. It is fitted with a fairey overdrive but I dont know what one it is, and I dont want to go up the road and experiment in fear of damaging something. Its not like an eaton twin spltter where you just get it into any gear to keep yourself going, then find the one you want.
I want to basically know where to have the gears for normal road driving with the free wheeling hubs disengaged, and being able to use the overdrive.
Sorry to sound dim, but if you dont ask you dont learn.
Ta, Paul

yer black nob is fer yer overdrive the others have bin covered on here before ,lotsotf times, and have a rather niffty description written somewhere so try a search

and yer free wheel hubs are a waste of time

slob said:

and yer free wheel hubs are a waste of time

Click to expand...

Thanks for that, sorted now! Why are the freewheeling hubs a waste of time though, apart from the fact that if you get stuck anywhere you gotta get out and dick around with a spanner, by which time the motor may already be sinking...

Freewheel Hubs, are pretty expensive, and dont really affect the LR that much, so the improvment and cost isnt really jusitified by performance.

See here;

http://www.landroverclub.net/Club/HTML/Free_wheeling_hubs.htm

I disagree on the FWH, with mine engage i can get to 55MPH and with then disengaged i can do 60MPH.
That alone makes them worth it.
They are only worthless to the newer landys with more power to spare but if you have only 77HP (probly alot less now) they are worth it.

Have a look at the attached for the knobs.

when i regulary drove series 2.25 petrol landies, maybe as many as ..oh.. 10 different ones in one day, 60-65 was about average top speed, some of them could get up to 70ish on a good down hill run.
yer FWH's are a pain cos yer got have them working maybe once a week or just to stop things seizing up. otherwise when you need them you wont be able to engage them, on top of that you have to ask if yer swivels will be getting a good lubbing,

if you forget to engage them then you have to get out and do it, which might mean getting knee deep in mud fer nowt.

if you think there are engaged cos you turned the nobby bit and some wag comes along when yer not looking and dis-engages them you'll be sat wondering why yer not moving.

theres bin a stack of comments on here about them and i'd say about 90% ish of the coments say they just int worth it