Santiago,
Greetings from Arizona, USA. Your carbine is what is know as the No. 1 carbine. It was made sometime after August 1870. This is because the extractor is what is known as the side slot extractor rather than a rotary extractor. It also has a flat portion of the breech block where it rolls under the rear of the barrel rather than concave.The numbers on the tang sides are assembly numbers, not serial numbers. With few exceptions, the black powder rifles were not serial numbered. Yours don't match probably the result of being refinished.
I don't know what information you have found about Rolling Blocks but, if you go to www.militaryrifles.com there is an excellent site about black powder rifles, including Rolling Blocks. From here go to "Black Powder Cartridge Military rifles". Open the site. Scroll down to "main rifles photo and information index". Check out the site but you will be interested in the "Argentina" section. When you open up this section, go down to the "Model 1866/75" section. Below the 1st photo is a link to "Remington Historical Info From Argentina" There, a Sr. Edwardo Fontenla has historical information regarding Rolling Block use by Argentina. Towards the bottom is an old wood cut showing the rifle and carbine. From this you can get an idea of what the forearm looked like. For good photos of what the wood on a Rolling Block carbine look like, go to WWW.GunBroker.com. Search for # 349992175.
Good luck!!!
Tom Jackson