I'll step out on a limb and answer until Jim has a chance to pop back in with any corrections.
At least until recently (because things can change rapidly in this world!) we were using Walbro brand pumps because over the last couple of years those were the most consistent and quiet of the ones we'd been using. And had been highly recommended from users out in the field too.
The style of pump (again, as far as I know) is the standard "Mustang" style of pump used on most Ford and other brand products from way back.
Now, some of the details may have changed, regarding which sock filter style and clamp and accessory pack, but the pump remains the same.
I believe that they are the standard 255lph pumps, but that's something I'm not sure of. At one point we had used a couple of the higher flow versions, but the 255's are good for some pretty decent performance engines without modification. So I'm guessing that's what we've stuck with.
Just as with the Sherman (or in the past, the EFI version of the NWMP/Sunset tanks) you can get a replacement pump in a pinch at any parts store just about anywhere by asking for almost whatever Ford application you feel like. There are probably 10 different part numbers for the Mustang alone, but most, if not all, utilize the same pump and only differ in regard to the extra fittings and size/shape of the sock filter that comes in the box.
I say "most" because there may be a special "SVO" or "SVT" model that utilizes a higher flow pump, but the fitment would be the same and even the most basic pump would feed most stock and stock-ish EFI builds.
Now after all that we'll see if I'm close, or off-base on some aspects when Jim checks back in. I know a lot of changes were contemplated during the development of the M1A1, and you can see most of them. But the pump I do believe is the same one as in the Sherman.
Paul