yeah I know the diffs have different mounting points on the upper arms....

if you swap the upper arms (ie EL diff with EL arms into an EF) that came with the diff will everything line up properly?

what I really want to know is are the mounting points on the chassis (ie where the arms connect to the body) the same on the EF and EL....
r the only changes ford made on the EL to the diff housing and arms and none to the actual body?

if they r then things r 100% interchangeable if u use all the parts (ie diff housing, arms, cables, watts link)

or to put another way - you can convert an EF to EL rear geometry by using EL parts?

The diff is a straight swap and will align correctly if you retain the upper control arms from the diff you are putting in, example use EL arms if you are putting in an EL. You will also need the handbrake cables as they are different betweeen the two. Note that the EL changes to the upper control arm length and the watts link pivot position on the diff were bought about by the Tickford changes for the EF XR's geometry.
Cheers
TW.