Full Tech Trees Revised and Improved

TxFire4305, on 30 April 2011 - 07:29 PM, said: What was the reasoning behind the decision to include the M46 which is a renamed version of the M26E2?
" Upgrade of existing M26. New compact transmission and engine with increased power to 810 hp (600 kW). Improved 90mm M3 gun, with bore evacuator and other modifications. Additional conversions beyond the prototype were redesignated as the T40, then were standardized as the M46 Patton. A total of 800 M26 tanks were converted to the M46.[81]" Zalooga 2000
Source: Zaloga, Steven J, Bryan, Tony, Laurier, Jim M26/M46 Pershing Tank 1943–1953, 2000, Osprey Publishing (New Vanguard 35), ISBN 1-84176-202-4.
Were the M47, and M48 considered and if so, why were they not chosen?