How long of a 1/2" diameter threaded rod do I need to replace the rear subframe mounts in the absence of MB special tools?

Thanks,
Sixto
91 300SE
87 300SDL
83 300SD

I had about a 15" length all set up with multiple washers and a proper diameter pipe bushing. Before I put it all on, I picked up a large screwdriver and "jimmy'd" the bushing out in about two minutes. All that time in preparing the homemade bushing puller for naught . Once you can get your hand (or water pump pliers) on the lower part of the bushing it rotates out fairly easily. Use the weight of the car as your bushing press when installing (with a little silicone lube). This assumes yours will be as shrunken with age as mine were (no jokes, please).

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)