side markers on a 69 gmc

[jd4300fel]

HI all,

I have a question for you.
I started to tear down my 69 gmc yesturday and was surprised that side markers had no light in them of even access for a light.
The markers that I took off had the year of 67 molded into them.
and there are no wire's hanging about.

So this now has me thinking of filling these holes, as well as smoothing the side's but since I live in california is this legal as a daily driver.

Any way thanks for your help.

Regards,

Mike