The ends were studs from the factory. Theres several differing opinions on why studs and not bolts were used. Some think it's to allow for expansion.
Heres a
pic of my 49 216 which is similar to the 235. I added short bolts to mine, primarily because I couldn't remember if they had them when I tore it down to send the head off for rebuild. I've put approx. 16k miles on it since without any intake or exhaust problems so it appears it didn't hurt.
Many just leave it with studs and not add the bolts.
If you add bolts, they need to be short.
