Maybe it is just me, but the idler arm you show on the left looks more like a '67 or newer idler arm.
IIRC, the idler arm for a '65 - '66 is the same for manual or PS. that new idler arm does not look correct.
For the $$$, I think this roller idler is one of the best mods I made to my '65 with manual steering. Opentracker Racing Products - Roller Idler Arms
I would call John at ORP and see what he thinks.
The MU idler may be fine, but I have no idea where they are made.
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