i think trinity made some red anodized "matt francis" castor blocks. the xxx-s blocks weren't exactly the same though. they didn't have the chamfered edges for spring clearance and the steering knuckles that came packaged with them only had one ball stud position. i think all the changes made were a running revision though, so whatevers out there should be current.
don't do aluminum though, you'll just break something else probably more expensive.