Barb, Grandpa had either a 130, or 131, Both are Stanley's double ended block planes. Also IMHO the hardest of all the Stanley planes to adjust, and keep adjusted.
Patrick's talk about them will be found here, scroll down, until you hit Stanley 130, the 131 is just behind it. I have one of each of them, and soon will be looking to sell them off, as I am not a fan, however they do seem to have some favor with collectors, and being your Grandpa's given to you by your Dad, well, that is something to hang onto. As a user you are going to be 1000 times happier with a nice Lee Valley block plane.
The idea was to offer a block plane, and also a bullnose plane. Worked and failed at the same time.. Yes they could be functional, but only with a lot of fiddling, and almost constant readjustment in use. Many of Stanleys unending block plane lineage was like this. Like I said a modern day Block from a reputable maker like Lee Valley/Veritas is going to be a joy to own, and use. I highly suggest just holding off, getting on the Lee Valley email list, and next time they offer a "Seconds" sale, jump in, and get a marvelous plane for a portion of retail. They sell no junk, and 99% of the people getting a blem will never quite figure out what was wrong with it. Any of their trash is smashed to pieces, so no one gets a bad Lee Valley, from them anyhow.