I dont have the part Number (Finis code) so i'll try and discribe it.

It's a section of the chassis on the n/s rear of the car which starts from the rear floor pan and goes back and up around the inner arch and the rear diff support frame bolts to it,i saw a picture of it at fords on their microfiche and it was labeled
number 2 of about 10 different parts of the rear assembly.

Hope this helps,if not i will try and find out the finis code.

p.s It's a 1988 2wd saff.

Thanx Roy