No they are all the same splines just the rear flange where it bolts onto the axle is diffrent on an atlas rather than an english. If you have a 5 speed box the front flange just goes futher into the box than the 4 speed unit from my experiance.

2.8i atlas axle with a lsd unit is still not cheap make sure that there is an lsd unit in it as they did not come with all 2.8i's.

As for beaing easy nothing in modding a car is easy?

If you look on ebay there are a few peolpe selling preparing a Mk2 escort for motorsport this will give u a lot of needed info yes it is rather old but the princales are the same.

Glad u can use a mig as with any old car you are going to need it. LOL