Penncraft branded tools were the earlier line and as MShaw said, made by New Britain. The later line was branded JCPenney and made by S-K. I have a set of Penncrafts I bought new to work on my first car in about 1970, still have and use them, and have expanded the set.
MShaw, do you perhaps know whether some of the wrenches I've been unable to find were ever made? : 16 & 18mm, 20mm and up, 8mm and down, 1 3/16, and combos under 3/8. In sockets I've found the small metrics down to 4mm, but not 16, 18 or 20 and up. Other than that, my sets are pretty complete.
I like them for sentimental reasons, but mainly because they're good tools. As for the lifetime guarantee, the last time I broke a ratchet, some years ago,(a rare occurrence) they were honoring it by giving a voucher for an equivalent Craftsman tool. Interesting note- New Britain also made some Craftsman tools.