Seems quite tricky to locate SnottyI'd like to know the answer to this one myself, for I have the same condition on my passenger side rear window on my '70.
Excellent! You sure about them fitting?Google is your friend, please use it. The B body's will work on C's. mopar window rollers - Google Search
I believe they are the ones with the bracket attached Alan I will check with my resto guy are these bespoke to the 66 300 ?What is broken, are the ones needed the one with the bracket built on to it, there are different ones with the bracket on it, pictures help.
Alan
Thanks Ken will take a lookHave you tried "mymopar.com" for a parts manual, on the left side of the page
Cheers
Ken
That's great big thanksView attachment 110758
Here is the qtr window frommy 65 Monaco.
The two broken guides are unique to C-bodies as best i can tell.
These are the two that everyone seems to need.
The square track slide is unique to C-body 2drs.
The broken front guide roller looks similar to B body pcs. but is a different part number for C bodies.
The rollers common to B bodies are the top two in horiz. slots.
I was fortunate to find a good used regulator, lower track guide & square slide roller online.
Re-assembly was fun.
Keep the guides and tracks greased!
Thanks for all your help guys I have now found all required parts.here is one each of two of the roller with bracket
1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 Dart Cuda R/H Qrt Window | eBay
Another pair
1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 Dart Cuda L/H Qrt Window rolle | eBay
These may not be the same as, do your research.
Alan