Other than the escort axle,some people have used volvo axles such as this guy:-
http://www.131abarth.com/my_131_rally.htmI've got an "abarthed" sport rally car which has a ford english diff.It's had the axle tubes chopped off and replaced with the fiat tubes,thus keeping the fiat stud pattern. Not sure how good it is though,as i've not driven it in anger yet. (The car's getting rebuilt in the not so distant future)
I've read the cars and car conversions mag from 1994 with the pink 131 sport rally car in it and the owner recons the extra weight of the sport compared to the escort makes the english axle break shafts. He went on to put a ford atlas axle on it and had no troubles since then.Dont know how much money an atlas axle would cost to build though.
If my axle aint any good,i'll be going the independant route via a BMW E30 325i sport diff and getting plenty of use out of the welder!
These have an LSD in them as standard and fetch around ?250 on ebay. Its the fitting part thats going to be interesting.
I'd forget about the 131 axle though as it's about as much use as a chocolate fireguard if you're going to give the car some grief,unless you have a vast supply of spare 131 axles stash away some where!