As far as this old FARMALL assembly worker telling you this fairy tale, He may have told you this story but it's ALL BS. Every tractor had a build sheet on it, with tractor serial number and branch and region order number, also had the ordering dealer's name & address, and the name of the person who ordered the tractor and his phone number unless it was a stock order for inventory. Every option was listed on that build sheet, via a 4 digit option code, there would also be a part number of the major part of that option, things like gas or diesel engine, TA or less TA, Cat 1 or 2 3-pt, 1 or 2 sets of remotes, and FARMALL could build HUNDREDS of variations with just tires alone. You could up-size, down-size, R-1, R-2-0, duals with matching brand size & ply to the tractor, or just bare duals, no tires. Every few stations on the lines, start & finish lines an inspector signed off that the right parts for the ordered options were on the tractor. FARMALL was like Burger-King, they built it YOUR WAY, and enough pairs of eyes looked at it before it shipped that it should have been what was ordered.
I worked at FARMALL for 5 years, fall 1976 to winter 1981, last three years in Material Scheduling, the 12-13 of us in that dept responsible for getting ALL the purchased parts into the plant, finished parts for assembly and raw castings, forgings, steel, etc for machining. We had an approved supplier, we bought stuff on annual blanket pot's and brought parts in daily, weekly, monthly as required. Seats during the 826 production time came from SEARS MANUFACTURING in Davenport. The3x88/5x88 series used a seat from Germany, name escapes me right now.
Your friend, buddy, whatever told you a fairy tale. I'm actually sorry you posted that, somebody will believe that BS, a lot of the new "REVOLUTIONARY" manufacturing methods small companies started using in the 2010's were being used in the 1960's at FARMALL. We had manufacturing cells, single employee running up to 4 machines, NC controlled lathes to turn gear blanks, heck, I had parts in 1979 I turned inventory about 350 times a year, that's about two turns per day, today even the automotive "JIT" plants with computerized reports to suppliers can't turn inventory that fast. I had a FAX machine right next to my desk ten years before most small companies owned one. I had a computer terminal by my desk that I could look at the branch & region order for a tractor, or I could send an e-mail to any other employee in the entire corporation, or I could check the entire corporation for inventory on ANY IH part number regardless of what product line, ag, truck, engines, construction, Solar. About 1979 IH had their own satellite in orbit for world-wide phone communications. Each employee had their own 5 or 6 digit I'd number, we could call from anywhere in the world to any IH phone number. Yep, sounds like a little 2-BIT company that didn't know what they were doing!