Silver: The Second Metal Coat:

In the kanto region,( after fighting all the 8 gym leaders in Jotho) in the power plant, go inside, talk to a man that asks you to trade his magneton for your dugtrio. The fastest way to get dugtrio is to catch a diglett in the digett's cave. Then train that digett till level 26 ( best way: fight elite four, as your diglett is from level 2-8) Then go back to the power plant, and trade with that man.If you look in the stats of that magneton, the item, it is holding a metal coat( maybe it depends, I am not sure, but I got it)