On some Sherman fuel tanks there is this triangular shape all along the length of the tank against the side wall with a cover over the actual tank, some others do not have these two features and not all have the generators mounted. Does anyone know more about these minute differences?

Not sure I follow your description - can you post photos?

The fuel tanks in a Sherman are in the sponsons either side of the engine compartment, and are not visible unless the vehicle has been taken apart.

The generator, with its own small fuel tank above it, sits on the left sponson shelf, at the rear of the fighting compartment - is this what you are referring to? The generator fuel tank had its own cover that attached to the rear wall (firewall between fighting compartment and engine compartment), so it looks more like a duct than a tank. AFAIK all the gun-equipped Shermans had these generators fitted, along with their small fuel tanks. Some Sherman-based vehicles such as the M32 TRV had the generators removed as part of the conversion process, since its primary function was to recharge batteries used by the radio when a tank was parked with the main engine off, and the space was put to other uses. I don't know how many variants of generator there were - I assume there may be several types with different details.

To the left of the equipment in the center some Shermans have what looks like an alternator or generator, as this pic shows not all have them. I am wondering why some do and some don't have them.

http://www.toadmanstankpictures.com/restore_60.jpg

Different pic from the same site with a few MS Paint lines to show the triangular shape and tank lid.

http://i1050.photobucket.com/albums/s402/InjectTheVenom02/restore_55_zpsgovyryuo.jpg

Your first pic (60 from Toadman's restoration of a Jumbo) is in the engine compartment looking aft. The GAA engine is not yet installed (the empty motor mount rises from the floor) and the thing on the wall is the drive for the cooling fan. (Note the pulleys at the far end). It was driven by direct PTO from the engine via a prop shaft. The fan itself is also missing.

The second pic is the same tank, in the engine compartment looking forward. The boxes on the left & right floor are the inboard fuel tanks unique to the M4A3 (other versions had different arrangements of tanks to fit the different engines) - note the filler neck and the hoses going out to the outboard sponson fuel tanks.

Scroll down on this page to get to the Ford GAA section, and there are tech manual diagrams of both items.

The generator I thought you were referring to is located the other side of the firewall.

That is the auxiliary generator on the driver side sponson

http://www.theshermantank.com/wp-content/uploads/different-style-aux-gen.png

On the cooling fan drive, towards the left in my first picture, sometimes there is a generator or alternator mounted between that and the vertical fuel tank on both sides, in this and many other pictures there is a blanking plate. 90 degrees to that you have the drive axle connected to the engine, on the other side you have the cooling fan pulley.

When would there be a blanking plate and when a generator/alternator?

This pic is of an M36 (M4A3 base), you can see the cylindrical devices on the drives. M36 only or also M4A3?

http://i1050.photobucket.com/albums/s402/InjectTheVenom02/Mobile%20Uploads/tmp_30263-IMAG0174-1341703376_zpspj5oedvb.jpg

I see what you mean! No idea, but there must have been at least one alternator on any tank. Not sure why that M36 has two, though...

I did a google and found a pic on a site THE SHERMAN TANK.com and there is a picture similar to the one you are showing with the generators installed, but is part of the engine removal manual and the generator(s) have been removed. There are plates on the power take off just like the one on the M4A3E2 under restoration. More than likely attached to protect the ends of the pto.

Was the M36 turret power hydraulic or electric?

Alternators came out a long time after war, in the 1960's. My folks had a 1965 or 6 VW Snail, uh, BUS that still had a generator. Darn that thing was slooooow.

It occurred to me that the main generator was attached to the transmission on standard M4's. There are some good pictures on the site I mentioned. Maybe moved to the pto's on the M36 due to the lower hull height?

Hey guys, glad to see my site is getting some use

The generator moved around depending on engine model and tank generator. They could be mounted under the turret basket with a belt driven from the drive shaft, this is how the M4A4 was and I think M4A2.

They could also be installed right at the back of the transmission also by belt drive. There were several different bracket setups for this. I don't have a manual for the M4/M4AA1 yet so I'm not sure of the early small hatch tanks had the generator under the turret like the A4 and A2.

The aux gen, both versions seemed to be installed in various spots in the drivers side sponson