eBay
 Nice versatile boat cradle, made by Waco scaffolding. Cleveland Ohio. Less chance of a stand kicking out, Folds flat when not in use. adjustable screw jacks. Used under our 36' Sea Ray 15,000#, 12'6" beam  boat. during bottom job, 6 built in screw jacks allowed lifting of boat off blocks to blast and paint
Service or storage use, 
Consider that if you have to block your boat and buy at least 4 jack stands at $75-$145 each, you'd not only be money ahead to buy this but it is safer, plus it has 2 keel jacks built in as well, another $150. saved. I bought this new direct from Waco near Cleveland, while I cannot locate my invoice I think this was about $650. stored indoors when not used.
Center of screw jack to center of screw jack on the long side is 14'.  It measures 8' wide center to center. Basically measure from the keel out 4' each side for placement.
The outer screw jack range is 27" to 43"
I'll try to arrange shipping if needed, the scissor stabilizers are about 14' long,
I am about 3 hrs South from lake erie area. near intersection of I-70 and I-75.
I'll be heading back to Florida, Punta Gorda area end of Sept, may be able to meet along the way,

Check out my other listings for boat stuff
I will be listing a set of stands, outer and keel powerboat., as well as plastic dock steps nib, tdx head system nib, Sea Ray f/glass cockpit table. Interprotect barrier system nib, Gal of Micron Extra black, inboard prop shafts new, misc rubrail s/s and alum.

Posted a Sea Ray sketch showing boat placement on cradle for reference, Our 36' was a twin inboard, if you have sterndrives the cradle would be moved back toward the transom. see posted question for more info,