Yes, your .44 is a 20" bbl'd Texan. (1963-64 Marauder's had a 16-1/4" bbl).
FWIW, the .44 Texan was only made 1965-67, and the saddle ring was issue from 1965-71.
The Texan's rounded lever loop was changed to a squared-off loop in 1984, with the addition of the crossbolt safety (CBS). (1984-87)
Actually the cross bolt safety came out in 1983.I have an 1983 TS with the CBS,18 1/2" barrel and the squared off leaver.
.
