I measured one here in the shop and it is 6 1/4" center to center., measuring along the part. The effective lever length of a stocker is about 5 7/8" with the stock bend. the overall length is about 8 1/8" measured along the part.
The one I measured is a stocker, part #3978040 GMT 46 A.
I believe that the repros are the same length, but they come flat, with no offset. I believe the center to center length is 6 1/4 on those.. They too, can be shortened some if you bend them. I have bent them up or down in order to get the right height, and I have bent them sideways in a dogleg to get them shorter to clear a tie rod.
You don't want to get too short or else you start losing turning radius.