Where is the casting number on my power brake booster?

[Gumby]

My car is a 1973 Dodge Challenger Rallye with Power Disc Brakes from the factory. My booster part number should be 3744 466.

 

[EV2RTSE]

Holding the booster upright with the check valve at about 10 o'clock, look around at the top edge like in this picture. This is from a 70 Bendix so it's a different part number than the one you have.

 

[Gumby]

Holding the booster upright with the check valve at about 10 o'clock, look around at the top edge like in this picture. This is from a 70 Bendix so it's a different part number than the one you have.

View attachment 134894

Thank you. I found a casting number there too.