I've looked at a lot of resources online and still can't get a real answer to this.
What marking on this relay reveals the amperage rating?

I think 0611 is a date code meaning June 2011. It's a standard micro relay pinout and the SH111 looks up to a common 20-amp relay used for a/c clutches and radiator fans.

what is the code for 30A?

No clue. Googling SH111 kept popping up a 4-seasons brand relay rated for 20-amps. Normally, the spec would be printed on it or at least a make/model to look it up. You looking to replace that one, or re-use that one elsewhere? Searching on "5-pin car micro relay" gets bunches of hits on Amazon.

For a blower motor relay mod.
But nice to know for when a relay swap fixes something.

Looking at https://www.boschautoparts.com/en/au...s/micro-relays, your diagram looks like either 0986AH0307 or 0332201107.

now to figure out how to identify 30A micro relays in the junkyard.

Almost not worth the effort to scrounge at the junkyard unless you're already there. They're pretty cheap on Amazon. $10 for a set of 5 relays with wiring harnesses.

Me being an electronics weenie, I would probably try a variable speed motor controller like this one.
or this

going there to get the relay block to house everything in. Saw a reference that the radio illumination relay is 40A.

And I am not sure that I trust $2 relays.

I forgot about this completely !

Have a 40A PWM for another project...adding A/C to a vehicle that came without

My search over there came up with 0986AH0322 and 0332011007.

I'm not aware of any way to determine the amp rating of a relay other than by consulting the manufacturer's product literature.

That is the same as what I am coming up with. And some of them the maker didn't leave a mark. As far as anything I have marked SH111, going to label them as 20A.