An assembly comprising: a first electrical connector comprising a plurality of differential signal contact pairs (123, 143), a second connector and a printed circuit board, the first and second connectors (100, 200) being situated on opposite sides (301, 302) of the printed circuit board, wherein the first and second connectors (100, 200) are interconnected by means of common vias of the printed circuit board, wherein a first one of the plurality of differential signal pairs of the first connector comprises first and second contact tails configured to be received in respective vias of the printed circuit board and a second one of the plurality of differential signal pairs comprises third and fourth contact tails that are received in respective vias (341, 343) of the printed circuit board; wherein the first electrical connector comprises a housing holding a plurality of leadframe assemblies (115, 135), each leadframe assembly comprising a respective centerline and contact tails distributed along the respective centerline; wherein the plurality of leadframe assemblies comprises second type leadframe assemblies having contact tails disposed in pairs along a respective centerline; wherein the second one of the differential signal contact pairs is on a second type leadframe assembly, characterized in that the plurality of leadframe assemblies comprises first type leadframe assemblies having contact tails jogged on opposite sides of the respective centerline; wherein the first one of the differential signal contact pairs are on a first type leadframe assembly, and disposed in the common vias. a first electrical connector comprising a plurality of differential signal contact pairs (123, 143), a second connector and a printed circuit board, the first and second connectors (100, 200) being situated on opposite sides (301, 302) of the printed circuit board, wherein the first and second connectors (100, 200) are interconnected by means of common vias of the printed circuit board, wherein a first one of the plurality of differential signal pairs of the first connector comprises first and second contact tails configured to be received in respective vias of the printed circuit board and a second one of the plurality of differential signal pairs comprises third and fourth contact tails that are received in respective vias (341, 343) of the printed circuit board; wherein the first electrical connector comprises a housing holding a plurality of leadframe assemblies (115, 135), each leadframe assembly comprising a respective centerline and contact tails distributed along the respective centerline; wherein the plurality of leadframe assemblies comprises second type leadframe assemblies having contact tails disposed in pairs along a respective centerline; wherein the second one of the differential signal contact pairs is on a second type leadframe assembly, characterized in that the plurality of leadframe assemblies comprises first type leadframe assemblies having contact tails jogged on opposite sides of the respective centerline; wherein the first one of the differential signal contact pairs are on a first type leadframe assembly, and disposed in the common vias.