1970 Challenger Bumper Filler Retainer brackets

[mtull]

I've seen a few sources stating the early built 1970 Challengers included brackets to hold the front bumper fillers in place.  Attached is an image from the ECS exhaust website.  I assumed at first they were referring to the outer rubber fillers between the bumper and fender but still can't envision how they are mounted to the bumper?  Has anyone seen these installed on a bumper?

Thank you 

[TWS]

I have not been able to find any data on when they were used.  However I do know of two Sep-Oct cars that did NOT have them. I would not be surprised to hear that they were not initially used, over the first few months they received complaints about the corner rubber bumpers slipping out of place.  Then added the brackets sometime during the 70 model year.  Then fixed the problem by going with the notched bumper / notched rubber locking design in 1971.  All speculation, perhaps we can start a thread on SPDs vs. equipped with the brackets.

Below is a pic of an original install...the brackets used the outer bumper bracket bolt, between the bracket and the bumper, and the blunt end of the bracket just pushed on the backside of the corner rubber, jamming it in place.

One interesting thing with these brackets....I have a few of them and they have a completely different part number stamped on them, yet otherwise identical.  It will take some digging to find them, but I will try in the next few days.

[mtull]

Thank you @TWS.  I never would have figured it out without your pic.  I have a SPD of 9-11-69 and no notches in the bumper where the fillers slide in.

[EV2RTSE]

My car has them, late March of 70 build. There's a pentastar and the #s 90718-210 and 10946, on both of them.

[mtull]

My car has them, late March of 70 build. There's a pentastar and the #s 90718-210 and 10946, on both of them.

Thank you.  Much appreciated info.
Ugh, Another hard part to find. 

[TWS]

@mtull. Are you sure your car came with them?  Original bumper with witness marks from the brackets?  As mentioned above, I know of two cars with SPDs near yours that did not.

[mtull]

@TWS good point. I'll have to take a closer look and see if any evidence still exists.  My car is Hamtramck built in case the plant informs any differences.

Thank you.

[R/T's 4 R/P]

The rubber bumper inserts progressively changed. The early rubber pieces were considerably smaller.
Possibly the change in those rubber part numbers could be used to track the timing of the use of the brackets.
The ones shown in the photo above are the larger style

[mtull]

The early rubber pieces were considerably smaller

Interesting.  My version of the parts book shows part numbers 2962346 and 2962347 however my fillers are numbered 2962344 and 2962345. 
Is this a case where the part number and molding number are different or do I have the wrong fillers?

Theoretically how would I compare part number shift over time?  Would I need multiple parts books with different publish dates?

Thank you for sharing your expertise.

[Mr Cuda]

My early filler with no notch nubs in the groove area are 2962344-5.
 The later ones with the notch nubs, are 3464064-5.
9/30 production,  no filler notch in bumper,  no filler support bracket.
 .

[mtull]

My early filler with no notch nubs in the groove area are 2962344-5.
 The later ones with the notch nubs, are 3464064-5.
9/30 production,  no filler notch in bumper,  no filler support bracket.
 .

Perfect!  Thank you for sharing that info.