1978 Mustang Swim platform brackets - Dimensions?

My recommendation to you would be do the measurements yourself. That way you know it will fit and know it will be right. As far as height up the transom, next time you have the boat in the water mark the waterline (from the water - obviously don't be hanging off the back of the boat....it will be 4 inches lower) Decide how far off the water you want the platform. Some folks mount them a few inches off the water. I mounted mine so the bottom of the platform is right on the water. As far as the bracket itself, there are two measurements. Vertical rise and swing. I was going to try to explain it in detail, but Alloy Marine does a better job than I could.

http://www.alloymarine.com/indexII/swing.htm

Swing doesn't have to be absolutely straight back. They can toe-in or toe-out, whatever fits your platform framework the best.

Note: In case you looked at my avatar and are wondering why the platform looks like it is sloping, it is. I am convinced I sent AM the right rise angle, and this is what I got. I wasn't happy with it, but instead of trying to convince them that they got it wrong I (after this picture was taken) routed out some "ramps" in my platform so that it sits level right on the water, now.