When I constructed this vehicle about 5 years ago, I ordered a 130, 300 Tdi galvanized frame, with a Td5 rear end, which meant I had to use a Td5 fuel tank. I found a list of parts on the Internet, and all was well until you filled the tank brim full – there was a leak from the top of the tank. I had repaired a previous tank so I knew what I was looking for. Unfortunately the 130 didn’t have am inspection plate in the floor so the tank had to be dropped out, and as it was a plastic tank, there was no drain, so I had to suck out all the fuel first – I didn’t add this bit as I got a bit messy with the diesel! The tool used is a Smoke Wizard, which is mainly used for emission control proposes, however for finding oil leaks in engines, gearboxes and axles it is invaluable. The smoke also carries a dye, so in extreme cases, a tiny leak can be found using an ultra violet light You must test engines, gearboxes and axles with no oil in them, and it is a lot better than looking for leaks with air and soapy water as it is clean and you can get to fix the repair straight away ... https://www.youtube.com/watch?v=2C5k9K5swTc