Uniform sizes stair stepped 10-24, 28, 32, 36, 40, 48 and 56. I know that doesn't answer your question. But I don't exactly know. And I believe it did change later.

Thanks, Ploughman. I thought there must be tighter thread pitches in size 10 bolts, but local hardware stores only stock 10-24 and 10-32 nuts. I bet it's 10-36. Maybe I'll special order both a 10-36 and a 10-40 just to be sure. Appreciate your help.

Mike

Mike if you have trouble finding something let me know. That fastener place I frequent moved recently and is closer to me now. They moved from Derby to Milford. I can see if they are open this Friday and make a run. I have both white felt and black felt mufflers. I've had the white felt one apart completely. But the black one has never been removed. The end threads on the black one are distorted and think this was a factory thing no? They need a die run over them or the end nut would just strip when removed. So I can only use the white pad knob as a test dummy. The threads on both do look the same. And a 10-24 nut did not fit it like yours. Can grab a few styles of nut and mail them to you. Or the website is https://www.nutty.com/

You can buy online with them as well. But we still need to know what the correct thread size is. You can look at what they have and see what might work the best. I thought a castle/split nut as you can zip some of the nubs off. Sort of replicates the original part too. The smallest I saw online was 1/4". So....:) more digging is needed. I know they have old odd lot stuff not online. Happy to help if you need a hand.

Peening the end of the shaft was done in Cleveland/Dayton. You have to file it out.

Very good to know thanks Jack.

Mike,

Think I have an extra bolt (as circled in the main pic)..

I'll confirm tomorrow..

Kelly

Thanks guys for all your input and opinions on this tiny subject.

Glenn: Let me know if you ever decipher the exact size of this thread. Even if Kelly (Rims) locates a spare for me, I still want to mount a nylon locking nut at the end of the shaft like the later white Fullerton mufflers have.

Keep me informed.

Mike

I will Mike. I'll go there Friday if they are open. *****eidt to add****** I just called and they are open friday 8-5. So I'll head up there. Hey Mike do you have a pic of what that end locknut looks like? I want one too for mine so I'll grab a few. If Kelly does not have that original nut let me know the type of nut you'd like to modify please. I can grab them for you and mail them with the locknuts. And most important we'll now know the thread size! :)

That is an American thread, but I forget the size. I have a tap and die in that size at home for chasing the threads. I'm traveling now so I can't check in my toolbox. The size is the same for all years, and the shaft on the throwoffs is the same size.