I measured mine at about 35", but the maximum that can fit within the slot is about 37".
Not absolutley positive mine is oem original (for a 71 cuda), but it must be close since it fits perfectly.
Do a search of the site for jack mast length. I did see some other measurements a few weeks ago when I was researching.
There are several good threads about jacks.
In the end I think there were many slight variations because of the vendors that supplied them back then, and how mopar handled their supplies, so I cant imagine a judge sweating an inch or two, but Ive been wrong before!