Here is a web site I found that provides some very good details about
early BW T-10's. According to the info shown, your ID decodes as:
W = Warner Transmission (manufacturer)
C = March (month of build)
5 = 5th day of March (day of the month built)
5 = 1965 (production year) *
3 = 3rd shift (shift of the day that built it)
* According to the listed production/use years being 1957-65 for Chevy's, I think the only plausible choice would be that year.
The tail housing date code I believe is actual 1964 based on the above note. It's may not be original to the transmission. Something used to repair/replace damaged or worn out parts which is common.
The site also shows other details such as drive ratios in each gear. Hope the info provides the help you needed.
