One reason our customer has chosen to build a DAX Rush De Dion LX is the convenience of being able to use a single donor car.

The Rush De Dion takes all its major components (front and rear suspension, steering column, axles and brakes) from the commonly available Ford Sierra. As builders of the budget LX spec. car, we will be using the Sierra engine and gearbox. The 2-litre Ford Pinto offers substantial performance in standard trim and - as the car we are building is capable of handling far more power - we can always upgrade it in the future.

So, for our car to live, another has to die. What are we looking for and where do we start? Well, if we can find a rusted out 2-litre Ford Sierra locally, that's the best solution. You might already have seen one standing unloved and unused in someone's driveway. Try knocking on their door and making an offer. Then there is Exchange and Mart, the local newspaper and Auto Trader to be checked.

Ideally, says Patrick, you're looking for a car which had all new mechanical components last week, but which has failed its MoT because of terminal rot and has a rough interior. Of course, you'll never find the perfect donor. Some of the mechanical parts are likely to be in as poor shape as the body, but at least you will then have something to refurbish or exchange - much cheaper than buying from scratch.

The chances are your donor won't be street legal, but if you do get the chance to drive it, even if it's only up and down the drive, take it. You can learn a lot about the condition of the mechanicals just from that, says Patrick.

Don't worry about trying to find one of the Sierra models with rear disc brakes if you're looking to build a Pinto-engined Rush. Patrick says the rear drums are well up to the job on such a light car - and it's a lot less hassle making the handbrake work properly.

Then, when you get it home it's time to start stripping. Patrick advises buying the donor in good time. Then you can strip off all the parts you need (or might need) and get everything checked, cleaned and painted and the decks cleared before stage one of your kit arrives. You have to decide what to keep and what to replace, but Patrick's hot tip is to never throw anything away. Then when you go looking for your new part, at least you'll have something to compare it with or, maybe, exchange it for.

You'll need to hire a spring compressor for removing the springs safely, Patrick points out, but there's no need to buy one. An industrial wash tub would also be extremely useful, but Patrick's tip here is to make one yourself by cutting the top off an old oil drum.

The engine for our budget build has been stripped and rebuilt by Patrick with new rings and gaskets, but has not been modified. If you've got the money in the budget for some engine work, though, his advice is that it's worth having it balanced first, then to go for a gas-flowed head.

It is most important to allow for contingencies in the budget, says Patrick. He would never build a kit-car without taking a good look at the engine. Better to find the problems at this stage rather than once it is in the car.

The standard 5-speed gearbox from the Sierra is also used. Patrick's advice is that it is cheaper to get an exchange box than have the one from the donor rebuilt, unless you can do it yourself. Differentials are very reliable, he says. Just remove the rear cover, have a good look for signs of wear or damage and replace the oil seals as a matter of course. If you have problems, you're very unlucky. Incidentally, with the rear cover removed, this is an ideal time to shorten to the central double-threaded boss, said Patrick. About 16mm (5/8") removed from its rear face is sufficient to provide the required clearance for the de dion tube.