Hi cowboylife
Please realize all what follows is theoretical. I have never done a switch as you suggest, but a little research leads me to believe it is indeed possible.
All the ARCA compatible QR clamps seem to connect to the ballhead stem the same way, with an Allen head bolt. Two reviewers on the Adorama and B & H websites seem to indicate what you suggest is possible:
"This MH-655 comes with a 3/8 screw . If your tripod , or tripod head , has a 1/4screw sticking up you'll need to order the 3/8-to-1/4 reducer bushing B&H # GIG1141 ($4.95) ."
"Mounts beautifully to Giottos 1001 ball head and replaces the "stock" circular top plate, leaving a low profile, clean look. Comes with special screw and allen wrench for that purpose. Very firm and steady with no play or wobble."
The design of the 655, 656, 657 and 658 is identical. They only vary in the length of the clamp jaws, and the stated weight bearing capacity. The 655 is 40mm long, the 656 50mm, the 657 60mm and the 658 90mm. The width of the clamp opening is constant to allow ARCA compatibility. The weight of the clamps increases with length of course, as does the stated capacity. There is a very small price spread on these clamps, amounting to less than $10 from smallest to largest.
For reasons unknown to me, Adorama has a lower price on both the clamps and the ballhead/QR clamp combinations as compared to B & H. Also the Adorama price structure on the clamps is odd, with the 655, 656 and 657 all costing the same.
Maxdave
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