Tonights clue......
Aircraft, Im thinking of...
1. incorporated some "tried and tested systems & equipments."
2.designers decided NOT to adopt a variable geometry which was internationally favored at that time.
3.had a all moving tailplane & standard rudder
4. production aircraft had a redesigned outer wing with the leading edge reduced to 45 degrees and greater span.
5.one proto type had 5 engines
6.flight tests began in 1964 but a lenghty development period delayed its service debut until early 1970's