Sausage

Yes you are correct. If they arent listed chances are it is sold with cover only and if your grommets dont have part numbers then that is a given.. What size diameter are they? Audi 32mm one is 07C103226 Gold Mk4 TDI 038103638K

https://volkswagen.7zap.com/en/rdw/lupo++lupo+3l+tdi/lu/2001-231/1/103-103055/ Looks like 038103638B

Maybe your map is too aggressive low down the revs and peak torque is too early or boost is spiking, the gearbox wont like it at all and tend to make noises to tell you. Try the stock map and see of the noise goes away. There is (on the 1.4 tdi at least) a heat shield that can rattle and drone on the gear cables but usually at idle, also PS pipes make a nice noise touching the subframe if not secured right.

http://wiki.ross-tech.com/wiki/index.php/17560/P1152/004434 Look for air leaks.

Crack or hole in the system of baffles loose in the silencer maybe, get someone to do the pedal while you rummage around on the floor looking for clues. Welcome btw....

if it seems like the lifters / tappets then you could try some additive. My TDI was getting a bit rattly, so i bunged some liqui moly lifter additive stuff in and it shut it right up.

if it sounds like it is from top end then lifters / tappets. You can probably pin it down to one cylinder just by listening to it. Bottom end will be more serious. Oil level / condition? If new oil was it right grade?

Best to still charge the battery right up using a charger as alternators dont like being overworked charging flat batteries.

It has been known for fuel to get contaminated and cause lots of problems for customers, pretty rare but it happens. Seawater getting in the fuel on the ship comes to mind that happened local to me a long while back. So rule out fuel 1st by checking or changing fuel filter etc. to see if it has muck or water in it.

Try and pin down where it is. Generally if you can feel it thru the steering wheel it is front, if you cant it is back. If you can feel oscillation on braking as well could be duff tyre, bent wheel etc. It could be nothing to do with wheels / tyres and might be the engine, so rev it in neutral to about 4000 rpm and see if it starts misbehaving.

Check for slop / binding at the shifter mech. You can move the selector thru all gears by hand, but probably need the cables off it first. https://www.ebay.co.uk/itm/163589140615 you can get the bushes in plastic for a lot cheaper.... While there check for slop on the tower as if that moves about it messes with the gear selection as well. It could also be the gear lever mech obstructed or worn.

Noice! I like the mk1s... Forced induction for the win.

0.8mm will be fine, you will be just doing overlapping spots for a lot of it anyway. Welding upside down is a pain in the ass (or ear when the weld blobs go in there) so get some height on the side if you can. Do some practice on your scrap, clean tight joints help a ton as does no wind if outside. watch some urchfab for panel welding technique:

How are they balanced? Do they have more meat on the back of the head area? They are a very marmite wheel and i fall into the disgust camp on them but those splitties do make them easier to stomach...

Amazed that got past the swear filter LOL. Best bargain was my black TDI hillclimb shed i am currently driving. I got a 6 speed TDI box for £1. No use to me, but i bid on it and got it.

Whatever i gain on one thing I lose on another so I find my smugness doesnt last for long, especially when I had the fluffy boo pikies lifting hundreds of £££s of my stuff last year.

Once moving just match the revs to road speed / gear and you can change gears easy enough without touching the clutch pedal. OK for a get you home but long term the syncros will have a hard time of it unless you are quite good at it.

No I havent done it yet, got all the bits, done all the reading and then procrastinated big time. Black TDI needs major overhaul now so either it or the red one will get the treatment. 3 pot mechanicals: 1.4 TDI engine mechanicals.pdf

02R gearbox fits you just have to shave the mounting lugs as there is webbing between them to fit the gearbox mount. Some ratios here: https://workshop-manuals.com/seat/leon-mk1/02r_5-speed/technical_data/gearbox_identification/code_letters_assembly_allocation_ratios_capacities/ VNT needs suitable n75 and mapping. He needs bigger injectors right off the bat if he wants to do this. Also the 4 pot flywheel wont be offset balanced to the 3 pot piston / crank assembly so either get that done somehow, or get the 3 pot flywheel machined and re pinned for 4 pot clutches or else just live with the vibration.

Yep, other variables are clutch not adjusted right so release bearing is always under some load or clutch faults. Input shaft spins in neutral at clutch bite point, so you can hear excessive bearing noise or rattles then if it has problem. If it only rattles when the car is moving then output shaft, differential side of things comes into play.

Clutch isnt either on or off so try some detective work on when the noise changes. At light touch on the pedal? At the bite point? At clutch released? Same thing coming back up the pedal travel from the floor. Release bearing isnt doing anything until you touch the pedal and move it into contact with the pressure plate. As you press the clutch in it is then under load and will make noise if it is worn. That will be a rotational scraping noise. A rattle there might be broken release bearing mount, broken clutch finger etc but will sound horrendous. If your rattle is coming in at the clutch bite point and then disappearing on clutch pedal down beyond bite point (clutch disengaged) then that is when input shaft on the gearbox starts and stops rotating. If so then gearbox.

Take it off for a proper job, no point leaving the metal bits in there.

No idea, I have not tried it on a lupo, had a back box fall off a mondeo it sounded great, the default mod when a yoof was to remove silencer and substitute something in its place. Probably a middle box delete instead then as my TDI only has rear box and sounds very nice.

Depends what kit you have access to and how knackered the thread is. Unless you have taps the right sizes or helicoil kit the right size it is probably just easier to source another sump. M14x1.5 it looks like. Sump off either way to clean it and get the bits of thread out. Maybe some metal repair stuff might work, but you'd still need to drill and tap that tbh. if you have a grinder you can make a rough tap out of an old bolt the right size thread by cutting slots down the thread for chip clearance and putting a taper on the nose of it, would work fine for softer stuff. I'd probably go M16x1.5 or M18x1.5 and get a sump plug to suit.

Oldstout, my suggestion was for someone who asked what different back boxes might sound like. So the cheapest option (which is always my favourite option) was to see what no back box sounded like first. That can then be moderated with a small silencer and / or large bore tail pipe.