I found one someone made that I used as a Pattern. Squared 2" tubing with a solid rod welded to each end. I removed the jacks lifting pad and welded the threaded rod that holds the lifting plate to the jack.
I made these lift bars as my student project in the welding class I took. They sit on the jack pad. The rear bar had to be notched for clearance at the ZF. Way over designed but hey, it was for welding practice. (Sorry about the lousy phone picture.)