The only true replica available of Eastwood's gun from The Good The Bad and The Ugly that exists but not without its flaws. (Namely the snake on the Blondie version.)
Uberti made the guns for the original movies and still makes guns to this day. Cimarron has taken an Uberti manufactured Colt 1851 Richards Navy replica and customized it so that it match the guns from The Good The Bad and the Ugly. (Both Blondie's with Snakes and Tuco's without Snakes.)
Tuco: Out of stock? Discontinued?
"[The model with two snakes instead of one] was an earlier release gun and production was ended in 2012 with the snake on both sides. Do not know how many were produced but it is not a special number. It retailed for approximately $940.00. Currently we only import and sell the same gun with the snake only on the right side.
Customer Service/Sales 830-997-9090
Cimarron Firearms Co"
It also appears that the snakes surface finish changed after 2012. Earlier photos show a less reflective snake being used for both sides but the newer models with a single snake show a single high polish version.
From the manufacturer
You can hang 'em high or paint the town red with this 1851 Navy cartridge conversion revolver. Either way, this spitting image replica of the 1851 Navy model used by the lead actor in the 1960s spaghetti westerns will surely set you apart from other sixgunners! Retaining a Civil War-era, black powder style loading lever, yet converted to handle modern factory smokeless cartridges in .38 Colt or .38 S&W Special, this 7 1/2-inch, octagonal barreled smokewagon is finished in blue and color casehardening, with a brass back strap and trigger guard. However, its handsome period varnished, walnut grips are uniquely inlaid with the Man with No Name's signature sterling silver rattlesnake, giving this revolver the appearance of being coiled and ready to strike! Here's a cartridge conversion sixgun, introduced by Cimarron that definitely stands out from the crowd!