My former coach was a 2006 Monaco Knight and it had the Weldex B&W cameras. The contrast wasn't so great so I wanted to switch them out with color. I contacted Weldex and got a replacement color 7" flat screen monitor and a rear color camera for about $500.
I left the side cameras B&W. The wiring was completely compatible.
The entire swap out only took about an hour and a half. The most trouble I had was getting the new monitor to mount in the hold left by the B&W CRT. The bracket they supply for the thinner LCD screen is not so great.
My new coach has a different system using an Audiovox Voyager AOM-7694 monitor and an Audiovox VCTT-130 Camera. I like it somewhat better than the Weldex. Having done some adjustment on it, I think the camera may be the same one that Weldex was using, but I can't be sure, but the wiring harness looked identical.
I would suggest you look at a Voyager system by Audiovox. A reseller may be able to advise you on the issue of wiring harness compatibility.
Voyager Rear Observation System by AudioVox