down a track in the track extrusion 19 into engagement with the two piece block 48 specifically the cable 32 is secured in an upper block 62 preferably formed of plastic a lower block 64 preferably formed of plastic is cooperable with the upper block 62 and is displaceable in a channel in the track extrusion 19 see fig7 a connecting plate 66 preferably formed of aluminum is fixed e g welded to the subframe 23 the connecting plate 66 acts to secure the upper and lower blocks 62 64 together the connecting plate 66 includes a knob 68 that extends through a threaded opening in the plate 66 and engages a hole 70 in the upper block 62 two connectors 72 such as screws or the like extend through the connecting plate 66 into threaded holes 74 in the lower block 64 the block 48 including the upper block 62 and the lower block 64 along with the connecting plate 66 together define a carriage assembly as the motor 30 drives the spiral wound cable 32 the cable 32 displaces the carriage assembly to open or close the window 22 a cross section of the carriage assembly is shown in fig7 in the event of motor failure or if it is otherwise.