As said, ensure you have all the parts before you start to put the diff' together.
Also, get some green slime, if you can get some. This will also be good for when you service your dampers too !!
Get a small container/cylinder that the body of the diff' will sit upright in. That way you will be able to let the diff stand on it, upright and not spill over when you put the oil in.
I have found the best way is to build the deep body of the diff first with outdrive,o ring and larger toothed gear and pin.
Start to put some of your desired oil in (1/3 full) Then put your 'criss-cross' assembly of smaller toothed pinions on their shafts, complete with spacer/washers. Ensure the two shafts are placed together on the flats machined in the shafts....this is very important !
Put these into the body and push fully down.
Top up just level with the top of the body (Don't 'domb' the oil in the body!)
Place the gasget in the lid along with the pulley and the outdrive and pin.
Ensure this seats nicely in the lid !! Can be difficult this. Try to keep the gasget dry for as long into the process as poss' !
Now, before you place the 'lid' on............. place the 2nd larger toothed pinion/wheel on the body/assembly. Make sure it seats well and is "in mesh" with the other pinions/wheels !! Push down on this wheel to ensure everything is fully in place. Now wait for the bubbles to dissapate and ensure the body is full of oil.......about 15 to 30 mins ! (Especially with 100 or 120,000 WT oil !)
Take a note of the direction of the drive slot in this last pulley as you will need to line up the pin in the outdrive which is already in the lid with this drive slot.
Tip: Try to make it horizontal or vertical. It makes it easier! Remember your lining up the screw holes aswell as the pin !!!!
Place the lid in position on top of the body and press together.
Now, make sure the lid is flat on the body !
Place in your screws and tighten criss-cross fasion. There should not be any need to tighten really hard. If the gasget is seated well and you have placed the lid on straight and firmly. Do the tightening of the screws in stages as this will help to seat the two mating surfaces together better.
Hope this all helps Frankie and the best of luck to you !1