Local Craigslist ad for 1976 DT400 for parts, for $200 firm! Oil tank, front and rear wheels, tank, front fender and engine with no cylinder, piston or carb, . 

I have a 74 DT250, my question is does the lower engine share parts do the wheels work with my model? I'searchedthe forums for days now, but can't find a definitive answer for interchangability of parts. Anybody got some wisdom for me?

  

The wheels should be a direct interchange. Same with forks, oil tank, most frame parts.

Center cases and crankshaft will be different.  Other internal engine parts are likely to work.  Best thing to do is compare the parts list for your 74 with the one for the 76.

Agreed. The motors have some interchangeable bits, bit the frame and running gear are mostly interchangeable.

Thanks for the info! I'll go to the bank, get some Yamadollars, hunt the bike down and bag it and tag it!

with a little luck you might get a 6 volt regulator in the deal and that will be good for your 250.  The engine will fit either frame has been my experience.
Doug

I stand corrected on the front wheel, though I believe the later wheel will fit. Same axle, so that’s not an issue. I have fit a 19“ front full hub wheel on a 75, so it should work fine.