If you cannot find the original style bracket, contact Alloy Marine
They offer a removable bracket for your boat that works very well. I have a set on my '89. I needed to remove the platform to fit in the garage, and now always tow with the platform removed and stored in the boat. I had to cut a notch in the platform to clear the lift rings - other than that, it's a pretty straigt forward install. I also installed transom tie downs on my trailer, and they are easy to use with the platform removed during transport.
Edit: Pretty positive that MC doesn't sell the brackets - you might post an WTB in the classifieds here on TT. You'll need the brackets for '87-'90 model year.