Re: Anyone know where I can find replacements for these "plates"?
 

Just use some nice thick grade 8 washers on each bolt. I did that to my SCM61 and it worked fine. They just hold the housing on the center section. I think the ones I used were about 1/2" washers, make sure they have a decent amount of area to bite on the center section, they were about 1/8" thick. Make sure they are grade 8 or higher.

Re: Anyone know where I can find replacements for these "plates"?
 

And dab a bit of threadlocker on there. I had my bolts back out causing the compressor housing to rock and take out the wheel. No fun.