[jeffschevelle]

Agree 100% with Darrell - if it is original and restorable, keep it.

And I never use an NOS part with a later part number than what came on the car.

And I would believe CRG before any online parts seller.

In the 67 AIM, the Z28 section does not show any change to frame mount brackets from regular V8 production parts. Section 6, Page B8, shows 3892733-34. So that should be correct for your 67. This is also confirmed in the parts books published in 1967 and 1968.

I don't have a 68 AIM, but the 67-68 parts books list the same numbers for 67s and 68s, and the same numbers were listed in the October 1968 book for 67s and 68s (after 69 production started). So I would assume they were the same parts for both 67s and 68s.

The other numbers you list -- 3955183(L) and 3980938(R) -- are way too high to be 67 parts. New 3-series part numbers issued during 67 production are 391xxxx at the highest (maybe a handful of low 392's).

Parts history books show:
- 3892733-34 was replaced (for service purposes) by 3955183-84 in May 1969.

The rest of this doe not apply to your cars, but here it is anyway --

3955183(L) and 3955184(R) appear in the early 1969 parts books for 69 307 and 327. They do not apply to 69 302's and 350's (which were 3945507-08), so would not be right for your Z's in any event.

3955183(L) and 3980938(R) appear in the 1969 AIM for standard V8 (307). But there is a "redrawn and redesigned" notation dated 8/6/69.

So based on all that, my GUESS would be 69 307's and 327's started with 3955183-84 brackets, then the right side got changed for some reason to 3980938 later in the year.