RICHARD J. - Ha-Ha! I made a frt mount dethatcher about 12-13 yrs ago. Sorry, No pic's available. It didn't last that long! While trimming & mowing around my biggest Maple tree it caught on an exposed root and I stopped JUST as it was about ready to enter my mower deck having lifted the whole frt of my CC off the ground as I drove ahead with the dethatcher pivoting UNDER the CC.
Suggestion - Make it l-o-n-g. It should extend at least two feet ahead of the pivot points, I used the frt pivots for the horizontal bars on my CC's mule drive assembly, they'e a sturdy 1/2" diameter rod. You'll also need some sort of castering gauge wheel just ahead of the bars with the dethatcher fingers on them. I bought hay rake teeth at my local Farm & Fleet for a New Holland hay baler, think they were about $2 each and have two teeth each. And they slide nicely over 1" galvanized pipe. A 1/4" x 1-1/2" cap screw & nut secure each tooth to the bar so they can swing freely. And a sturdy 3/8" dia. U-Bolt clamps the pipes to the frame very nicely, I got a couple u-bolts from my local Case/IH dealer. I forget how I had the lift mechanism rigged to raise the dethatcher when I raised the mower, think it was just a long cable attached to the lift handle extending down to the dethatcher frame.
I took my frt mount dethatcher and redesigned it & widened it to attach to the Cat O 3-pt on my 982 CC, works great on there. Only problem is My lawn vacuum goes on my CC #72 so I can't mow, dethatch, & vacuum all at the same time now. Ahhh More seat time!