Pivot lock shoe
Hey there. This is a 15-191 Pivot Shoe. it works with either the 3/8" thick Series 165 coil springs or the 1/2" thick Series 160 springs. See which matches what you need.
That '35' probably refers to the travel length of the coil spring, and the pertinent spring to identify the weight likely has faded. Could you weigh the window sash these coil spring support? We can calculate the needed spring weights from there (see the video below). Also, if you can tell me the width of the spring (1/2" or 3/8") I should be able to calculate what Series you need also.
In that case, go with the 160-06 6.5 pound springs, one for each side of the window. That will give you 13 pounds of total support (being within 1 pound of the exact weight works fine). If you need new coil covers, see the 15-150S. Let me know if you have further questions.
