I won't be of any help answering your question but knowing the year of the engine/manifold will likely help. Early manifolds used alignment rings. I don't know if/when that stopped.

The alignment rings are for the intake manifold. As Tiny noted the year is needed. My parts book was not a lot of help as it listed pilot studs for 49-55 but my 54 has threaded studs. Hopefully someone can advise the original usage by year. 

Thanks! I should have included the dates!

Head 3836848 dated B194. This confuses me as from what I read this head was built from 56 thru 62 but the date code is February 19 1954?

engine dated K305, solid lifter truck engine.

@robert-keck I agree on the date code however that is the head I am using on the 54 engine in my 51 and I used bolts for the ends of the exhaust manifold. I believe that was what was on it before rebuilding . I don't know if that is the original set-up but I do think it is better .

I recall reading that a change was made from studs with nuts to alignment studs only, to help with the warping that is common to the exhaust manifolds. I tried to find the earlier discussion but was unsuccessful. My two 41 engines have studs with nuts while my 48 and 50 do not have nuts. These are all 216 engines. 

@michael-falise 

I too remember reading the same thing, but don't know where.

I do know that the illustration of the engine on page 85 of the '29-'54 master parts book clearly shows no nut or bolt at the front end of the exhaust manifold.

Just a stud.

@ole-olson This is pretty interesting!
My 29 to 42 parts manual shows studs with nuts.

My 57 manual shows alignment studs!

@robert-keck 

And my '46 (truck) has studs with brass nuts.  🙂

My 41 that I bought in 79 and my 47 that I bought in 68, and still have just had the alignment studs. 

Thanks everyone for your replies! 
It’s interesting to learn of the different options.

bob

Here is a thread from the old VCCA site started by @Tiny.  It looks like alignment guides/studs on some heads.

https://vccachat.org/ubbthreads.php/ubb/showflat/Number/433926/

The early engines had studs with the extra long brass nuts. They developed a special 9/16" wrench that was bent into a horseshoe shape to be able to tighten the one closest to the firewall. I am not sure when they switched to just straight alignment pins but most of the engines starting in the 50s had them.