The gearbox breather cap on a Peugeot 407 typically resembles a small cylindrical or dome-shaped cap made of plastic or rubber. It often features a vented design to allow for the release of pressure while preventing contaminants from entering the gearbox. The cap is usually located on the top or side of the gearbox and may have identification markings or grooves for easier handling during maintenance.
The identification stamp on a Peugeot 307 gearbox is typically located on the side of the gearbox casing. It can often be found near the mounting points or on the flat surfaces of the gearbox. Look for a series of letters and numbers that indicate the gearbox type and specifications. If you're having trouble finding it, referring to the vehicle's service manual or consulting a professional may help.
Look into the engine compartment it's the big silver thing attached to the engine. aaaaaahahahahaha
The gearbox breather hose.
The Peugeot 406 is made by french car makers. This is large and spacious and sedan type look. The lines are sleek and finished. The interior can be tailored to fit you.
they are black in colour and have a multiplug connection on the side of them
on the right hand side of the engine as you look at it, remove the airbox to gain access, what does it look like
Under the air breather... Remove air breather and look down right there and not too bad to get to. Hope it helps.
look on the ebay
get gearbox number off gear box and look it up online.other than that try counting the different positions of gears
due to the complexeity of an auto gearbox i would suggest a replacment of the gearbox as the cost of repairs will out way the cost of a good secondhand unit. so to save the head ache go to an auction look for a written off car the same as yours and salvage for the parts needed. or look for a specialist breaker for a new gearbox.
look on the valve cover right behind the oil cap. if it is like mine it may just have a breather that looks like a cap in it's place. you just remover the breather thingy or pcv whatever the case may be and insert the new valve. if it just has the breather cap you may have to rerout an extra vacuum line to it from the main vac source or something. Anyways, hope this helps
Look at the V5 document.