The Type III was placed in service, replacing the Type I, in September 1972. The Type I is most common; the Type III design was used in 1973 and after. The 1972 Type II is expensive in top grades, as is the 1776–1976 Type I from Philadelphia, which was only available in mint sets. Some 1971-S proof pieces (and a few uncirculated 1971-S) have the serifs at the foot of the "R" in "LIBERTY" missing; this is dubbed the "peg leg" variety. The serifs are missing on all 1972-S, both uncirculated and proof. After the Mint obtained better steel for dies, the serifs returned for all of the remaining non-Bicentennial coinage, from all mints, though the leg of the R was shortened, and also for the Type II Bicentennial (the Type I lacks serifs on the R). Gasparro was often trying to improve the detail of Eisenhower's head during the coin's tenure, and as the R is the letter closest to it, these changes were most likely made in an effort to improve the flow of metal as the coins were struck. In 1974 and again in 1977, the Denver Mint struck a small number of pieces on silver-clad planchets, or blanks. Both times, these came from planchets which had been shipped from the San Francisco Assay Office to Denver. The first ones in 1974 were found independently by two Las Vegas blackjack dealers. The 1974 planchets were initially intended to be used for "brown Ike" proof strikings; Mint policy then was that rejected silver proof planchets were to be used for uncirculated "blue Ikes", but these were placed in the bin for rejected copper-nickel proof planchets, intended to be shipped to be coined for circulation at Denver. The 1977 pieces resulted from pieces rejected for Bicentennial silver proof use, which were again placed in the wrong bin (they should have been melted, as the Mint was no longer striking silver uncirculated Eisenhower dollars). Between 10 and 20 of each date are known. Wexler, Crawford, and Flynn report an even rarer 1776–1976-D dollar in silver, but state that none have been offered at auction or submitted to the major coin grading services. Bowers notes that the Morgan dollar (struck between 1878 and 1921) was not widely collected at the time, only to become very popular later, and suggests that one day, the turn of the Eisenhower dollar will come.