I cannot find Part 126F in the Hazardous Materials Regulations. Where did it go?

You will not find Part 126F or a reference to 126F in the regulations. HM–126F was the docket number given to the rulemaking dealing with training for hazardous materials employees. HM–126F was the number assigned to that specific rulemaking. Once the rulemaking was completed and the changes went into effect (the changes were made to the CFR) the number 126F was retired. The training requirements resulting from HM–126F are found in Subpart H of Part 172 and 177.816.