ShawnF350:
You are experiencing one of the most infuriating aspects of engineering: designed obsolescence.
Having worked in engineering, I know firsthand how this works and why it`s done. Design "improvements" (AKA changes) to parts happen all the time. Unfortunately, engineers and their counterparts, CAD technicians, will "update" a part for a variety of reasons. Here`s some examples why changes are made:
1) Old Part did not fit new model of existing or old machine, so it was revised.
2) Machine or Assembly Shop made change to part (IE, engineering on the fly) to make it easier to machine or assemble (BUT NEVER consulted engineering to authorize that department to do so, but does tell the CAD technician to make the change for future part production Or it never gets changed (like GM ignition switches))
3) Increase durability or reduce failure from R&D test run or computer simulation (Finite Element Analysis or Motion Kinematics) (this is why high production parts will fail in x-amount of time, usually the time of the machine warranty, to within a month or cycle of constant use. It is no longer guess work; it`s designed to last JUST that long. Which is why the International Harvester refrigerator from 1960 inherited from grandpa out in your garage is still running, and why your new refrigerator in your kitchen from Sears will die in 3-5 years).
4) Materials are no longer available (like a cast iron part or pattern that was thrown out because it was not used or sold in the last three years and hence, not profitable to inventory or stock.)
We (CAD technicians) were always told to research the part change (engineering change) and determine if it was backwards compatible on old machines/equipment. Guess how often that happened when deadlines and department efficiency ratings came into play?? Most times a new part number was taken out to avoid doing this "research". Now you know why you may have an old machine and the owner`s manual has a list of replacement parts that when you call customer service with that old part number, it has been replaced by a new part number. So the old part was a machined cast iron part; new part is a machined weldment (or cast modern plastic) part that looks completely "different" than the part you are replacing. We even had to write on hand drawings (or type on CAD drawings ) in big BOLD RED lettering:
OBSOLETE PART
IFU PART No. XXXXXX-XXX
Date: 25 MAY 16 By: Your Initials
The IFU stood for "In Future Use". We used to joke that it really meant that the engineer or designer admits "I F***ed Up". We laugh about it to this day.
OK, so this engineering experience is really "more than you wanted to know", but it does give insight what happens to parts, why parts change, and why you may have a different part number for an old part.
