Called Doug at double tee (firewallfittings.com) to ask the questions I sent on Saturday. He answered as hoped and promised to send more details later. He sent me a part drawing instead of trying to describe it and it answered my final questions. I placed an order for one of the 6100-0.240s and two of the 4200-0.375. It may be a month or more before I get the 4200's, but I can drill holes now and expect them to fit. Made a final decision about where to locate the two EMT wire feedthrough. Drilled undersized holes to approximately match the flat width and then filed larger as needed. Looked at the double tee drawing and tolerances. Tried to find thread sizes. Learned more about thread specifications, but decided to stop looking and just go with the 1.125" hole -0 +0.030 we discussed. Looked at my step drills and then at the hydraulic punch. The step drills are too small. The punch will just barely fit where I need it, but the sizes are wrong. Decided to buy a larger step drill at harbor freight along with larger sanding drums than my Dremel tool to use in smoothing out or enlarging the holes if needed.