Hunter couldn't find a holster size 34 as far back as 1966. I doubt this one is that old. I've seen them eBay, but can't find anything on the web about what it fits. I bought it for my 6" single six, but it's to short. I am passing it on to a guy for a bearcat, I guess we'll see if it fits when he gets it.
In looking at a number of older Hunter holster fit guides, it looks like an 1100, size 34 was intended for a 6-inch Standard Ruger .22 Auto. (Model RST6)
For a 4-inch Standard Ruger .22 Auto, the 1100 that fits is a size 24.
Here's a picture of an 1100, size 34 I found on Gunbroker:
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=475815823