It's a shame I don't have my book Viscount, Comet & Concorde by Stewart Wilson as this book outlines it very well.
However, so does wikipedia - http://en.wikipedia.org/wiki/Vickers_Viscount
700 - the first production version, 1,381 hp (1,030 kW) engines, 287 built
700D - 1,576 hp (1,175 kW) engines
724 - 15 sold to Trans Canada Airlines (TCA) of Canada, included more electrical power, a new fuel system, and cold weather operation provisions.
745 - 40 sold to Capital Airlines of the USA
757 - 35 for Trans Canada Airlines with more powerful 1,600 hp (1,193 kW) Dart 510 engines
771D - improved 770D
800 - fuselage stretched 3 ft 10 in (1.2 m), 67 built
810 - 1,991 hp (1,485 kW) engines, 84 built
The TCA version was the first North American version. Most of the updates requested by TCA (for certification, operational reasons) were incorporated as standard from then on.
The Capitol Airlines Viscounts were later in service with United when United took over Capitol. UA
actually sent some back to Vickers, but liked them so much re-purchased them!
The Viscount is, I believe, still the most successful British airliner from the amount produced.