joeninety, centre road always have plenty of CA20 boxes and usually a few stumpys too. it'll take you a while, but i'd do the old take two boxes out, split em and pay for one trick.
you'll be in for a bit of fun splitting them, i can't remember the exact tricks, but i know that it takes a lot of wiggling and prying. it will look like it has split on the gear selecter side of the "sandwich plate" but the bellhousing does definately comes off by itself. oh, i just remembered... you need to take all of the obvious nuts and bolts out, and the plate that goes around the input shaft... then heres the doosy - there's a circlipy kinda thing around the shaft you need to remove. and before you put it together you need a different bearing. but i have the part no. of that, let me know when you get there.
sounds a bit muddled, it might make better sense when you are doing it all.
good luck!