Did you google the model number? You can get a wealth of information. You can download the original manual. That manual has parts and part numbers (also available on replacement part websites). You need a grass bag frame (#446432) and the bag (#439332) for rear catch. Next, google those part numbers and you will find some replacement parts. When older equipment does not have original OEM parts available, there are substitute part numbers which work the same. Often, certain parts carry across through generations of models and uniformly fit across certain brands. So the parts may be by other names, like Husqvarna or MTD, which may have been the actual companies that produced the mowers under the Craftsman label name.

Thanks for the reply. You can still get the frame, but the bag is discontinued. What I need is to find the bag (used or not), or something that will fit to replace the original bag. Thank you for the info.

Funny, I actually have a couple extra 917 series mowers, one 917370910.

A quick search says that Craftsman #439332 was superceded by Husqvarna #583541301 which was superceded by Husqvarna #580943406 (may require superceded frame):

You may have to search for yet even newer part #s that are available. Good luck.

Thank you very much. I'll be looking it up now.