I have no idea whether these blades are old Allis brand or something someone threw in there that was close enough. Agco parts books don't give dimensions and NOS parts #'s aren't much help anymore.

I've measured the less beat and mangled blade and come up with 23"L x 3.5"W x 0.5 thickness.

They have a drop or offset of 2" or 2.5 counting the thickness of the blade.

Doing a google search,  I have not had any luck so far finding blades with these exact dimensions....closest I can get are ones that are only 3" wide......so,  I guess thinner ones would/could work???

There are longer ones available of the 3.5 width, but taking some measuresments, looks like 23L" would be the maximum anyway.

Also, does anyone know the style/type and size of the original bolts used to hold the blades on?

On mine, someone took a regular hex head bolt, 7/8 dia. and drilled a hole in the ends for the cotter pins. For bushings, crude scrap metal chunks/pieces, in two haves, were wedged in between. I'm guessing the bolts originally were some sort of big carriage head type as the first plate they go through had square holes but mine got worn and rounded out.

I've been reading through previous posts on this topic going back some 20 years, but have yet to find one where someone mentions what exactly ended up working for them , either with modern part #s or at least dimensions/specs.

Thanks for any help.

Big carriage bolt, with a bushing through the blade, and a cotter pin hole. There is a center bar that went between the 2 bolts, spanning the upper bar that bolts the upper bar to the gearbox.  There was also an option for corn stalk shredding, all of the above (carriage bolts actually had 2 cotter pin holes) plus a set of zero offset blades that mounted above the offset lower blades.  IMHO, never needed as one set of blades shredded cornstalks just fine...

I'm thinking the original blades were 4" wide though, as the reinforcement plates the blades sandwich between are this wide.

What is the significance of a greater offset , other than putting the blade ends closer to the ground?  If the original offset was closer to 3 to 4", that seems like it would put the blades down near the edge of the sides of the deck and make them more likely to hitting things like stones sticking out of the dirt.

I would get the 24" blades, and some new bushings and pins, mount them and see if they hit.  If they don't hit, take them out for a test cut.  if at any point they do start bangin, you can always cut a little off with a chop saw...

Check the ORC, on the drive line to be sure its operating correctly.  You should be able to hear it clicking, when you step on the clutch, at high rpm, as the mower starts to slow down.  Also check the rattle clutch, fwd of the ORC, on the drive line.  Don't over grease the rattle clutch, or it will give you all kinds of trouble...