The only listing I have for a Savage 101 is a single shot 22 pistol. That has been out of production for years, but the rear sight is a simple dovetail V notch that a competent gunsmith could fit. If you are asking about a rifle, please check the model number, and check with Customer Service for Savage, and check gunpartscorp website.
Savage 325c rear peep?
There are a few places you can find a Rear sights for a Savage Model 120. The most popular place to look would be online or a gun store.
Numrich gun parts corp.They may be found on the web.
http://www.e-gunparts.com/products.asp?chrMasterModel=089Zz22-410&MC=
S&W, e-gunparts.com, Brownell's
Sometimes it on the top of the barrel near the rear sight. Sometimes it's on the side of the barrel.
The standard mod 70 had a Winchester bead front sight on a ramp base with a sight cover. The standard rear sight was a Winchester 22G open sight. The rifles chambered for .375 H&H Mag had the Lyman 6W folding rear sight. Model 70 National Match (chambered for .30-06 only) had a Lyman No. 77 front sight on a forged ramp sight base and a Lyman No. 48WH rear sight. All receivers were tapped and drilled for popular scope and iron sights. The Model 70 Super Grade had a Redfield full gold bead front sight on a ramp with sight cover and a Winchester 22G open rear sight. (with acknowledgement to The Gun Digest, seventh edition, 1953)
They had a Small round knurled peep sight
Start with gunpartscorp.com then eBay and auctionarms.com
Try gun shops, gun shows, pawn shops, want ads, egunparts.
The "P" designates peep rear sight & ramp front sight, not sure of the "G" designation.
Your eye is the rear sight.