A jack?

A tyre inflation kit rather than a spare wheel lol

Didn't know a model T had a tyre inflation kit :P

Yeah it was called a mallet and a bucket of water... If you don't know what I mean, watch the 100th episode of wheeler dealers lol

steering wheel

Didn't know a model T had a tyre inflation kit :P

Let's consult Top Gear for some factual information on the Model T:

http://youtu.be/_amZsf8A1Lo?t=5m49s

Haha, I love top gear but the words top gear and factual together are amusing. They quote numbers provided by manufacturers which are inaccurate to real world lol there's little they can day that is truly factual, it's like getting your info from Wikipedia, he said she said that's it so it must be right lol

SEATBELT

Haha, but no...

Crankshaft?

Nope

DRIVERS SEAT

Right clue round-up with some things in bold to try and help:

I could see straight through what the manager overseeing the deal was trying to say.

It's still a car part.

The setting of the clue is a bit of a windup, don't read too much in to it.

At this rate, jeebs is going to complain about my conundrum to someone like ofcom, haha.

This part is on just about every car ever built, including the model T, but it is not unique to Fords.

If I make this any clearer I'll get pulled up by the ASA for false advertising that this is a conundrum, lol.

wing mirror

radiator

starter motor

None of those

BOLLOX

Openable windows?

Looking for a specific part, rather than feature.

Crank handle?

Nope

This is a part which is hidden out of sight and there are always an even number of them on the car.

Led lights?

led lights on a model t lol.

fuses/board.