SRT,
With your serial number being 559,xxx it would have come issued with earlier features than you now have on it.
The .U. stamped on the leftside of your stock means that stock went thru the post WWII rebuild program. Underwood was the contractor that rebuilt it. The stock being marked SC B, was made by Sprague & Carleton Co for a IBM carbine. That 559,xxx may have been placed in that stock during the rebuild or years later by a different owner. No way to know. The carbine does have the later parts on it that usually show it's been thru an upgrade/rebuild.

As Dave HH said.... Dumping the metal handguard and flash hider would benefit it's value.

To post pictures.....
I just put mine in my Photo Bucket then copy the IMG and paste it in my posting. Always PREVIEW the POST to make sure you have them in there, before posting the reply.

You can compare your carbine and stock by looking at auctions on GunBroker, just type in M1icon carbine in the search box.....
Guns - Online Gun Auction - Guns at GunBroker.com


You can also search Ebay for current auctions for m1 carbine stocks and some parts.
m1 carbine items - Get great deals on Collectibles, Sporting Goods items on eBay.com!
Try looking in the left column on the Ebay listings under REFINE SEARCH.......scroll down to and check the box next to COMPLETED LISTINGS. This will give you an idea of what similar stocks, parts, etc sold for.

Beware of many FAKE parts on Ebay.

HTH,
Charlie-painter777
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