The system in my 06 Crescendo is a power gear system. If you have the same,
the jacks are available.
One example:
https://www.ebay.com.au/itm/new-powe...-/252034665782
Attached is the manual and a parts list for the Power Gear system. Hope it helps.
These folks seem like they might be a big help
https://www.arizonarvpartscenter.com...rch=%20DN12989
Here's their PDF of PNs and obsolete jacks.
http://arizonarvparts.com/powergear/JackIDChart.pdf