RockAuto mistakenly lists the 2266 series motor mounts for '64-'66 Dart V8s- this is incorrect. Those mounts are for '67-'72 small blocks.
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What you need are the 2338 series mounts (which are correctly listed under '65 Barracuda... huh.)
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Currently out of stock at RA, but once you have the correct number you can look elsewhere.
(PS- It'll be a cold day in Hades that I pay almost $70 for a set of rubber mounts from Classic... if they're even in stock)
If you strike out finding some in stock, read this:
https://earlycuda.org/techdocs/JimBowenTheHolyGrailofMotorMounts.pdf
Both the 2469 and 2710 isolators are a big improvement over the hard to find originals, and for $5-$10 bucks a piece it's a no-brainer.
I personally used the 2469s and they fit and work perfectly.