In the Academy Sherman/Grant, kits etc., we get a choice of 2 different skids- the "normal" ones and the ones that look like a hump-back bridge! Which tanks came with these? I've not noticed them in any pics.

Thanx, Stevie.

There were actually three styles of skids (Tasca offers all of them as options). The first was a symmetrical hump, seen only on a few pilot vehicles, the second was an asymmetrical humped skid that resembled a wave about to break, and the third (final) type had the front edge of the skid folded over itself like a breaking wave. The first type probably didn't go overseas. The second style were used for a short time in 1942 right after the redesigned bogie was introduced with the trailing return roller arm. You have to really hunt to find them, as there weren't that many tanks that had them, and the heavy shadows present in most pictures make them hard to spot.
I've seen them on some early Direct Vision M4's, both Pressed Steel Car and Baldwin-built vehicles. They are also present on some early model M4's with the redesigned periscopic drivers' hoods. A PSC-built Sherman used at Los Alamos has the early style skids but the later, solid drivers' hoods. These skids may also be present on other early Sherman variants, but I haven't been hunting for them. Since the skids were a replaceable item, they are rare on preserved vehicles, as the "obsolete" skids could be unbolted and replaced during routine upgrading.
Sorry if this is maddeningly vague, but parts were introduced at different times at different assembly plants, and sometimes old parts reappeared on the assembly line when old inventory turned up.

Vague? That was not vague in the slightest. That was very helpful. Thank you very much.

Stevie.