Can I adjust cruise contorl speed slower? 1997 GMC

I'm pretty sure you can't. the automakers don't want you using it at those slow speeds.

Nope. The speed controls are not real stable at that low speed. Most of the cruise controls don't function below about 30.

Is it 4wd? You can put it in 4 low and idle speed is about 5 mph. It is on my 1500 z71. I'm assuming your in a hay field tossing bales onto a trailer while the truck drives itself?

NO, on the 4wd. YES, on the hay

Helping a friend, some years ago. We were pitching rocks off his field, one hot summer day. He had a boy, about seven, driving the tractor. Not tall enough yet to push the clutch. I thought that was a bit risky.

Can you even set a fast idle on these modern trucks? If you can that might be the ticket. 5 MPH would be awfully fast for that kind of work. That's a pretty fast walking clip.

fast idle would only work if you had a "granny gear" or some type of real low gearing. Otherwise you would be going about 15-20 mph down hill and about 5 mph up hill.

Well, I was thinking most hay fields are flat, but then I suppose in wet country they do cut and stack on hilly country too.

Also, it would depend on the transmission. Doesn't the Allison in a 3/4 ton Chevy truck also allow it to engine brake? My 2007 does when I turn on the tow haul mode.. I never tried it at slow speeds, and I noticed on 6% or steeper grades it still accelerates some at higher speeds. If that was a real issue though I would switch it into manual mode and put it in the gear I wanted. I do know not all Allisons have a manual mode. My 2003 3/4 does not.

Of course I have not played with the type of problem the OP has described for use in a modern truck. In the old days we used to track across the desert when somebody was lost by putting my dad's "jpv" ('41 Bantam) in gear and then getting out and following the sign occasionally going back to the jeep and correcting the steering.

Bob La Londe