The "36 after Model 7" stands for the year of manufacture (1936). They also were made in a 8" and 8-1/2" size. Early models were cast rather than forged, later models have vinyl coated handles. The pouch style also changed over the years. Besides several different jaws there was a tubing cutter and grip clamp attachments as well as a small screwdriver (two variations) marked "The E-F Angle Screwdriver"
According to an article by Herb Page published In The Fine Tool Journal the first models were made by Flash Sales Corp. ) (1921? to 1933), then American Plierwrench Corp. (1933 to 1952), then Eifel Products Co. (1952 to approx 1965), then after Joseph Eifel's death the American Supply Co. Plierwrench Division (1965 to 1970), then for a short time Plierench Tools Inc., then Masterform Tool Co., and finally Galland Henning Nopak (1980 to present time).
See DATAMP for several patents issued to Joseph Eifel at:
http://www.datamp.org/patents/displayIndex.php?start=0I have at least 20 Eifel pliers, all different styles or markings.