check out rally design online. they have some stuff that shows what the 5 'links' are iirc.

on a std solid rear axled ford like mk1/2 'scort, the axle is connected to the shell by the leaf springs. these 'control' the sideways movement of the axle, the fore and aft movement, and of course the up and down movement. not very well though.

the first step to improving the axle location is to add 2 forward facing links. these were fitted to the rs2000 as standard and are often called anti-tramp bars as it is said that they help to stop the leaf spring winding up which makes the axle tramp. personally i think that's bollox and axle tramping occurs when you don't have enough damping for the stength of spring that you have.

you can then add the turrets to the shell to have coil over spring and damper units, which gives you a wider choice of spring rates and ride height adjustment. you can then eliminate the leaf springs altogether, but then you need something to stop the axle moving sideways. a panhard rod connects one side of the axle to one side of the shell, a watts linkage is pictured above and connects to both sides of the shell. then you also need another 2 links to stop the axle wanting to rotate (these with the previos 2 'anti-tramp bars' are your 4 links).