What is the thread size for PTO nuts & bolts on AC G

alliumdream

New User
While working on my G's I keep running into this problem only with the fine threaded parts. NC nuts and bolts screw in fine. For example, the studs/nuts and bolts that connect the PTO body to the transfer case/bell housing. I ordered a thread ID gauge but in the meantime does anyone know what thread standard these are?

Another place I had the same problem is the 5/8 (i think) stud that connects the drawbar on the bottom of the tractor. Also the bolts that connect the drawbar bracket to the engine block.

Thank you guys for any help.
 

I should rephrase my question. Does anyone know if only UNC and UNF threads were used on the Allis Chalmers tractors, and specifically the G, or were other thread standards used, and do you know what they might be?
 
I've never seen anything other than UNC or UNF on most any old equipment. I think that drawbar stud is 3/4 on the G. Sometimes fine threads will get flattened a little from taking them out over rust or dirt. Doesn't take much to distort them so the nut will not go on.
 

Thank you Mike.

I ordered some UNF (7/16-20) for the PTO. Can't get anything but UNC at the big box stores any more.
 
Some times folks in doing "restoration" or repair might tap a hole in a metric size or even use a metric fastener.
 
Really? I can find them all over. Only ones I had trouble finding were some 9/16 UNC for pulling the brake drums. Finally found them at an OLD hardware store and he had boxes of them.
 

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