Broken speedo bolt hole

New to me 1996 Cherokee (4.0L/Ax-15 manual 2wd) was having issues with the speedo. It was reading as high as 30 mph over actual speed. So I took it upon myself to check the speed sending unit attached in the rear tail of the transmission. While loosening the bolt holding the unit into the case the bolt hole blew out and now I have no way to reinstall the bolt. I assume the case is aluminum but correct me if I'm wrong. If anyone can suggest tips, tricks or ideas on how to secure the speed sending unit I'm all ears. I'm new to this forum, so I can't attach pictures.

When you say "blew out" do you mean the threads have failed ?

I am not familiar with this exact problem, but Heli-Coil thread repair kits work well in other XJ Cherokee locations.

Does it have a bolt broken off in it or is it stripped ? a picture would help .