There should have been a threaded part on those studs. Sounds like the po cut them off trying to get the shocks off. You should be able to repair it by replacing the upper stud with Monroe hardware kit #P19, which is the same parts that you can use to adapt shock to the rear. This style stud will pass through the frame and is held in with a locking nut. They're usually included with shocks for '73-'87 Chevy and GMC trucks, but you should be able to get them separatly.
