Trying to drop the tranny to change the clutch but the 2 transmission crossmember bolts are screwed.

When you put a wrench on the nut, the nut along with the stud spins and I have no access to the other end to hold it. What do you suggest I do?

 

Don't worry. The threaded part is just a long stud. Just take the hole stud out. You'll have to wrench on it for a while but it will come right out. Make sure to have the trans supported and the drive shaft removed first.