My shifter is nuts!

Actually, the nuts on the factory Inland shifter keep coming loose. I've had a few instances where a shop put the car on a lift, then commented they found the shifter nuts loose, in one case almost falling off. In each case, they re-tightened the nuts. Apparently those nuts keep loosening.

Suggestions for a more permanent fix? I'm thinking nylocks, but hope to benefit from experience here. BTW, I have never crawled under the car to see what nuts (bolts?) the mechanics are talking about- I should do that, eh?