i am in need of a set of springs for the rearend..
i am looking for 56 to 57" in length...what yr would that be? thanlx in advance

56" springs came on some 1/2 ton trucks (generally the "heavy half variety), most 3/4 tons (but not all), and all 1 tons. This should be true from 73 up to the point where they changed the body and frame (88?). When they changed, it went to longer rear springs (64"?).

That said, 80s (not sure the exact range) Ford F150 springs have 2.5" wide springs (3" was available too) that are 57" long and the pin is 25" from the front eye. GM springs have the pin 26" from the front eye and are also 2.5" wide.