Heater Core replacement

OK below are the details of what I was able to search on. All 65-69 Darts use same core, even the AC model is about the same and interchanges with the non AC models. But I have not seen a listing for a 273 in a 64 Dart.

Are they the same units as a 65-69 cars? I think they are but not sure 100% :read2:

Specs for 65-69 Darts
Make: CHRYSLER
Core Size: 8 x 6 x 2
Inlet: 5/8
Outlet: 5/8
OE Number: 2277535
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INTERCHANGE INFORMATION
399104 can only be used to replace the following competitor's parts:
Type: Competitor: Part Number: Comments:
CHRYSLER 2277535 Can only be used to replace with Proliance Part Number
CHRYSLER 3744266 Can only be used to replace with Proliance Part Number
EVERCO 2212 Can only be used to replace with Proliance Part Number
FEDCO 2-088 Can only be used to replace with Proliance Part Number
FOUR SEASONS 94503 Can only be used to replace with Proliance Part Number
MODINE 4R700288 Can only be used to replace with Proliance Part Number
MURRAY 279201 Can only be used to replace with Proliance Part Number
STANT NEW PN 9104 Can only be used to replace with Proliance Part Number
STANT OLD PN 90104 Can only be used to replace with Proliance Part Number
VISTEON 9104 Can only be used to replace with Proliance Part Number


64
No listing

65
PROLIANCE Part # 399104
FOUR SEASONS Part # 94503 with AC

66
PROLIANCE Part # 399104
FOUR SEASONS Part # 94503 with AC

67
PROLIANCE Part # 399104
FOUR SEASONS Part # 94503 with AC

68-69 same as above
70 and up has a different part number