Take a look at this site.
https://www.gamainc.com/?post_type=product
Gama Electronics made all the remote control systems that were on these rigs, and as you scroll through their site, there are quite a few different remotes pictured, so you might be able to locate one that will work. You might even call them to ask. You might need the numbers off the receiver that is normally located on the ceiling in the front storage compartment. For what it's worth, after a couple times using the one that came with our rig, I tossed the remote in a drawer, never to be used again, just found it to be too much of a hassle to use and it burned through batteries much too fast.