Shaffer's 1950 ,
You say , When would a Thrust Bearing be replaced? Every time Cam gear is changed?
I kinda' think you are trying to self rationalize a reason for not finding or buying a new Thrust Bearing .
I have no dog in this fight......so ,as they say , ' have it your way ' .
It makes no difference to me whether you get a new one or ' nickel & dime ' yourself & use the old one .
The Thrust Bearing ( support ) prevents the camshaft from moving & rotating in all directions
except the for rotational motion of the camshaft .
In my opinion , it is critical in importance to have a new camshaft Thrust Bearing .
It's just my way of looking at the choice of new -vs- use the old one .
It could make the difference between a good running engine & a not so good running engine .
It's your choice.......just hope you make the right choice .
Other's will be along with their opinion's .
George
'54 3600