Frank, pretty much the entire run were converted to DD's. The combination of big hatches in the hull and the loaders hatch in the turret was considered attractive when facing the possibility that you might have to escape in even more of a hurry than usual...

Your 2 surviving references are the Slapton Sherman and the one pictured above, at the museum just south of Port En Bessin. Unfortunately Honnicutt doesn't really have much in his book, and you'll find more on line.

There is also a grainy picture knocking around of one being used to recover an M10 - this has had the skirts cut off, but you can still see the weld line around the hull the same as the Slapton one. This one has rubber block tracks for some reason (and is busy digging a hole for itself in the mud as a result), but DD's were issued with steel chevron tracks to enable them to manoeuvre on and off the landing craft. There is a picture of one knocked out on Omaha beach as well, but its even worse quality - you can make out the hatches by the way they open forward, but that's about it.

Dave Zollo also posted a lot of good big hatch DD references on the UK site a while back, with details like the cast in hull armour (75mm big hatches were still dry stowage), the taller headlights and guards (to clear the screen) and various other bits and bobs.

I can also drop off a CD of the pictures I took at the museum last year if you are interested (too many and too big to post here or try to force feed into Photobucket).

Still not seen a non DD converted big hatch 75mm Sherman in the wild, best you'd get is maybe a pic of one on test at APG in Maryland?