Looks like Bruce has the answer.

Here is the opening in my '54 3104:
> Cowl Inner Panel Heater Opening 1
> Cowl Inner Panel Heater Opening 2

See FAM Section 1, Sheet 5.00. Also 1954 Accessories Installation Manual p. 47. The 1951 Accessories Installation Manual is close, but not quite the same as the 1954 Manual.
> 1951 Heater Installation

You might check to see if dash mat has shifted which may cause the opening for the blower motor to be off. Your aftermarket generic blower motor is probably a little smaller diameter than the original motor, so that will give you a little more wiggle room.

- Lonnie

- Lonnie
My '54 3104
Photos that I have shared on Stovebolt via PhotoBucket are no longer available. Please contact me if you want a photo from an old post.
lonniecook [at] aol [dot] com. I sold my '54 3104 12/12/2017, but I still visit Stovebolt.

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