Hi i have an Ford EL with an open diff and i got and EL Farimont Ghia LSD Diff, and i want to know how to install it and what i have to do.

My car is an auto as well and will this affect my ECU? Like the shift points?

Thanks

The Ghia LSD will be a 3.45:1 ratio.
The open diff is probably 3.23 or 3.08.

So yes, it will affect your shift points.
You will need to get hold of an EL Ghia ECU, or get a J3 chip with changes written in it for the new diff ratio.
You will also need to get the correct gear for the speedo transducer.

The speedo transducer (red cable on top of your gearbox) should have a Grey 22 tooth gear on the metal part sticking into the gearbox itself, for 3:45 ratio. Otherwise your speedo will be out.