According to Don Wilkerson's book "The Post War Single Action Army 1976-1986" the seperateable cylinder bushing was dropped in favor to the press fitted cylinder bushing because of lower production costs. But also according to him the seperate cylinder bushing wasn't necessary anymore because of better quality of the steel used to produce the cylinders in the 3rd Gen. Colt SAA. In former times it was less expensive to change a cylinder bushing instead of a complete cylinder when due to a steel made of less quality the cylinder was worn out and had a loose fit to the base pin. (Hope I expressed myself correctly - I'm from Germany).
So that is the reason why I won't hesitate to buy an early but not too early 3rd. Gen. Colt SAA.
Interesting for those who would like to buy a Colt SAA is this page:
http://www.collectorsfirearms.com/admin/show_inventory.php?catID=13
