The 1987 Shimano Tourney TY10 was one of Shimano’s very basic derailleurs - it offered no SIS indexing, no Centeron pulley - nothing but your basic Skylark package. The only small change is the move of the cable clamp onto the outer parallelogram plate.
To keep costs down in the face of the advancing Taiwanese and Chinese competition, the TY10 was made in Singapore and also has noticeably tackier chrome than, say, the 1981 Shimano RS.
This example is a long cage version.
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