That link didn't technically "solve" my issue, but it WAS valuable information to get me where I needed to get.

Problem is, I don't use CADMEP for "production", I'm using Revit, and using Fabrication, and CADMEP is merely my platform to customize our services in Revit.

Workflow:

1. I route all piping in my Revit model using default Revit Pipe Types, just to get routings approved

2. At a later date, when the design gets more detailed, I grab all my Revit piping, click Design to Fabrication, select the service, boom, it all changes to fabrication, and then I start getting into the nuts and bolts of piping.

What I was running into was that my Tee was set for Branch-90, and a Weld-olet was set for StabInSocket. For some reason, the Design to Fabrication was ignoring Branch-90 (Tee) and going straight for StabInSocket (WOL) and I couldn't figure out what made it choose.

I created a new Button, Branch-90, and in the rules, I set it to be the substitute for StabInSocket. Works, remains to be seen if that's the recommended approach, but it works.