Last question, so I hope about my bike. I thank you for your answers.

I'm going to order some seals for my bike but my concern is, where should I get them from?

I think I got the last set from "Bikebuzzard" on Ebay when I rebuilt the motor 4 years ago. Again this motor only has about eight hours on it and now I have a bad seal. Is there a recommendation, or what do I need to watch out for when it comes to purchasing a new set of seals along with a clutch cover gasket to make the replacement complete?

That makes sense.  Those aftermarket crank seals sold by Bike Buzzard and others are the right size, but not the correct special "dual lip" seals Yamaha used.   DEET or Enduronut might still have some?

P.S.  I sent you a private message on a OEM set I found for a great price.   If I were you, I would buy them NOW.  They are more or less made of unobtainium and once they get sold, could be months, years, or maybe even never that they show up again?

Now that a set has been ordered by Hackman101, here is the link for anyone else interested in a set of OEM quality seals for the 1974 DT250/360 that has the "castle turret bump" dual lip crank seals.

Ebay engine seal set

That's a good deal on set of seals for the 1974 250 & 360. I'm certain I've paid more than that for a single seal for my DT360 in the past. If one buys the kit for a 74 DT 250 make sure you request the correct size right side seal. From what the description states the kit will be shipped with a 38mm ID right side seal (DT360) but can be substituted with a 40mm ID right side seal (DT250) on request. 

It would be best to measure your right side seal ID before ordering. They may be gone by the time you read this so it may be a mute point!

I've ordered probably 5 of those sets of seals. I used them in my 360. Just want to report
the time from Canada to my door in Calif was about 9-10 days if anybody is wondering.