Joey, The rear frame section of your car seems different due to what appears to be an accident - The comparison pics you show have a bend in the frame at the rear wheel hump this would have been from a fairly significant wreck to have bent the frame like that. You are using what is obviously damage to compare and say it doesn't match. It does. It is a 26 Buick frame. It was left there after being stripped for parts - like if a mechanic wanted a new engine for a car, pulled them out of a wrecked junker and threw the rest away in the trash pile for old parts in the yard. there are multiple cars' parts out there -lending to the trash pile theory. Also -why you found parts in the stream - parts were often tossed in the same place you dumped your oil. your grandfather was using the stream as a trashpit. The buick must have been to heavy to throw in..You have said he was a mechanic - I think we can say he worked on a '26 Buick, a model T, something with roll up windows, something from 1931 and an old stove or heater. and maybe something else in his long career. I appreciate your desire to call a spade a rare jade shovel from the most exotic hardware store - but it's a spade. Just a spade.