What is London Underground 1973 Stock?
{{Infobox Underground stock | name = 1973 Stock | image = File:1973 Tube Stock Hillingdon.jpg | imagealt = | imagesize = 300 | caption = A 1973 Stock train at [[London Borough of Hillingdon|Hillingdon]] | type = Deep-level tube | lines = {{rbox|Piccadilly line|Piccaddily line|#{{LUL colour|Piccadilly}}}} (1973 – present)<br> | manufacturer = [[Metro-Cammell]] | carlength = DM {{convert|17.473|m|ftin|abbr=on|sigfig=4}}<br>T/UNDM {{convert|17.676|m|ftin|abbr=on|sigfig=4}} | trainlength = {{convert|106.810|m|ftin|abbr=on|sigfig=4}} | width = {{convert|2.629|m|ftin|abbr=on|sigfig=4}} | height = {{convert|2.888|m|ftin|abbr=on|sigfig=4}} }} The '''1973 Tube Stock''' is the [[electric multiple unit]] (train) used on the [[Piccadilly line]] of the [[London Underground]]. It was introduced into service 1975 with the extension of the line to [[Hatton Cross station|Hatton Cross]]. Another extension was constructed to [[Heathrow Terminals 2 & 3 tube station|Heathrow Central]] in 1977. A total of 86 six-car trains were made. The trains were built by Metro-Cammell. [[Category:London Underground electric multiple units]]