Disco 1 R380 Gearbox change, Check List & other parts

Hey troops,

just had my 3rd Disco not more than 2-3 weeks and the bloody gearbox has gone...gutted!
Transfer box in neutral and changing through the gears is ok till you get to 4th then crunches / bangs / rattles / all the good stuff.
Can't afford to pay £1500 for a Ashford Transmission unit however nice they are and the labour, as this is nearly double what I paid for her.

Not drive-able so have sourced another from a disco that is getting broken with 107,000 on the clock. Question is.....

1, How can I check what the gearbox is like without being able to drive it, they say that when they drove it back that it was fine, must be better then mine with 172K on the clock.
Is there a test that i can do while it's on the deck?

2, While I've I'm changing the box, what else should I be changing while I'm there.
I've watched loads of videos on other people doing it and made some notes.

i.e.
Clutch
Friction Plate
Clutch Release Bearing
Heavy Duty release fork (went in other disco but garage did this)
Crank Oil seal
Bronze bush on crank (can't find the part number for this)
Clutch Cylinder (leaking anyway)
UV's on props(mine have around 2-3 mm play on them)
Adjust the reverse light switch as I've got to hold it for the light to come on.
Extent the breather pipes

Thinking from what others have been saying this is going to be a 2 day job and shed loads of lifting.
If you can think of anything else that I've missed would you be kind enough to mention it please

Ta in advance!
Heggars

theres no certain test but check input shaft isnt too loose ,you can turn it whilst selecting each gear in turn
spigot bush is 8566l
reverse light if you need to push stick over is a worn selector yoke
wouldnt do the rear main oil seal unless obviously leaking

Magic thanks Martin,
Got all the part numbers i need now, better do the reverse light switch when she's on the deck as i've just read it's a bar steward of a job to reach.
Noted on the oil seal, i'll order one just in case, but not seen evidence of this as the arse end of the engine is covered in sh/te, i'm thinking the steering box oil has flung everywhere.
The reservoir was empty when i picked her up, getting another steering box too.

Any tips on second hand ones while i've got you please?

H

second hand gear boxes or steering boxes, buy either from a reputable knowlegable trader, i can give you a number if you want one

I know that it could be a lot of work, and that i might have to do it again at some point.
just need to get the truck on the road asap, and funds aren't there at the mo.
£100 for both is pretty good, my friends mate who breaks them.

Worth a punt for the cost, even if it lasts for 6 months gives me time to shop around for a decent replacement, i'll give you a shout if it gets to that.
Hopefully get some photo's up when i get going on her.

H

Oils and new nuts & bolts for the props. And a grease gun