Quadrajet Secondary Throttle Rod

[400HO68]

I have noticed two different styles of secondary throttle rods on late 60's Pontiac Quadrajets.  How do I determine which was used by the factory for a '68 Firebird carb?

One uses extra 90 degree bends on the end to capture it on the primary end.
The other is held in place with an add-on clip on the primary end.
The secondary end appears the same on both.

Were both types used by Rochester when built? 
Is the type used determined by the date of manufacture or carb application?
Is the clip version only used as a repair part because it is easier to install without disassembly of much of the throttle body? 
Here are photos of each part:

https://quadrajetparts.com/images/products/rochester-quadrajet-parts/quadrajet-linkage/quadrajet-other-linkage/Q3170-wl.jpg

https://quadrajetparts.com/used-secondary-throttle-quadrajet-p-2375.html

[Kenth]

Clip style rod is 1:st design replaced by the second design rod for some 1968 and all later Q-jets.
Service rods are clip style for easier mount.

[400HO68]

Thank you Kenth.   Now it makes sense.  I have looked at photos of numerous '67-69 Pontiac carbs from numerous internet sources trying to find a correlation of dates to rod type but so many are rebuilds I could not figure it out.  I did see, what looked like, survivor Quadrajets from '68 with either type. A mid-year change explains that. 

I am going to have a correct '68 carb restored to put on my Firebird.  I assume then that a clip style rod on an end of January built car should be fine.  Depending on when the switch over happened at Rochester and stock depleted for my part number, the later design might be okay too. 

[Mr.Pontiac]

yep, really weird, there are 2 types, bends in completely differant angles. one inner and one outer,