My R serial 16233 DJ - 904L or 316L?

[renfield]

I have a 16233 R serial, 1988.

I'm trying to determine if it's 904L or 316L - I have read that the changeover for most models happened in 1987, but would like to know if people strongly believe or know for certain that the Datejust changed at this time?

Is my R serial 16233 904L?

Thank you.


(EDIT: Yes, that's right. I've been lurking here since Feb 2011, and this is my first post. Weird, I know.)

[Alpino]

.

All 162xx DJ models are made of 904L . So is yours ...