if the diff is from a 2.8 it won't fit
the one that you want for a direct replacement like for like is frmo the 2.9 sierra/granada as it has the same ratio as the cossie one of 3.62:1

as for the shafts, they are longer, i can't rememebr exactly how much longer but i measured some up for charlie (jimmy) luciano a few weeks back for his to compare

it's something to do with them not popping out if the car is lowered too much as they are longer, and therefore have a greater range of movement than the normal cossie ones

the downside is that sometiems they will be too long and cause other issues like hitting the insides of the cv's at the longest point