My Catalina 27 has the original standard rig. The foot is a rope-in-slot arrangement, and the mast has what I measured as about 3/4" internal slides. Does anyone have pictures of these slides (yours, not mine)? There's a guy who wants to sell me a used main and he's having a hard time telling "slugs" from "slides" and "internal" from "external", and I want to get this right before I enrich all of you UPS stockholders. My boat is 2.5 hours away; hopefully yours is closer.