Thanks for the effort. So far I am striking out on finding any info. Looks like I may have to do some modification myself. Unfortunately it looks like some parts are no longer available, at least on the Sears site.
For what it's worth, I went to the Chat Line one the Sears Parts site, and here's what I got out of that.
"Please wait for a Sears Customer Service Representative to respond. This chat may be monitored or recorded for quality assurance purposes. Your average wait is 4 seconds. Thank you for holding.
You are now chatting with Brian D. How may I help you?
You: Hi Brian, I have a question about an older garden tractor and snow blower, if they will work together.
You: the tractor is model # 917.255980, and the snowblower is model # 842.240722
You: Opps, my name is Bruce W.
Brian D: Bruce the snowblower is a 40" and the mower deck is a 44" they will not fit.
You: Thanks, is there a place where I can readily find the models of snowblowers that will fit the 917.255980?
Brian D: I recommend visiting Sears.com or call 800-349-4358.
You: Thanks Brian, I'll try that."