Thank you for providing all of that information!
The correct replacement shackle straps for your 2010 Cruiser RV Shadow Cruiser 18' Travel Trailer is the Replacement Standard Shackle Link # LC122487 which measures 2-1/4" center to center of the 9/16" holes so it will be right at 1/8" shorter than your current shackle straps, but is the closest option and will work perfectly.
I included a video of the # LC122487 for you to take a look at. view full answer...