Well, leave it to FedEx to bugger up your day... they did their normal thing of trying to deliver to the wrong place twice (after me calling them) then claiming I'm not in. AAAAARRRRRRGGGGG!!!!!!!
In more fun news, in my stash of parts I had the gasket for between the gearbox casing and the bell housing, and the replacement front mainshaft and roller bearing. Yay my ebay habit!
I've found the culprit for the rattle, as suspected it was the front mainshaft bearing. The bearing cage had fractured! Not sure what could have caused it, I checked all the teeth, the other bearings and synchros and there was no other evidence of damage.
I've stripped the box, pulled everything apart and cleaned it up. Pressed out the offending bearing, replaced the roller bearing in the middle of the main shaft and installed the new front bearing, assembled the clusters, casing, selector forks, top housing and reverse gear. Torqued it all down to spec.
The good news is the input shaft is solid now, as my friend up in Boston would say, the gearbox is like 'buttah', smooth as a cashmere codpiece and devoid of play. There's very little backlash in the lay shaft to the main shaft assembly. All that's left to do is assemble the rear cover and release mechanism when I get the gaskets.
I've told Fedex to not try and redeliver, I will go to them in the morning to pick up the package as I can't trust them to follow a simple delivery address.
I can't wait to put Beryl back together