I have a 73 dt3.  The exhaust is secured to the bike in two spots from what I can tell, one is on the bottom and is rusted off and the other is the muffler stay that connects at the top of the rear shock.  The muffler stay appears to be two pieces of metal with a piece of rubber between them.  The rubber has come apart from the metal on one side.  I have not found this part available for purchase so I am looking into ways to fix it.  Was thinking of using epoxy, any thoughts/suggestions? 

This is on fleabay, but stupidly expensive.

YAMAHA NOS VINTAGE - MUFFLER STAY 1 - DT - MX - RT - YZ - 308-14771-00 | eBay

I got a couple of repops for my bikes from a fleabay seller called motodave, but looks like he no longer sells, at least not under that username.

Will this one suffice, at least for now. Might need the larger hole broaching out though.  Yam part number 565-14771-00-00

Ebay listing number. 384661683729.  £13.  No idea of the hole spacing though.  May require extra bracketry bolting to it to make everything line up correctly.

I once tried epoxy on the bonded rubber anti vibratioǹ bobbins on a Honda CB900FA taillight.  It quickly failed even though thet were upright with the weight bearing down on them under compression.   With the rubber in shear, not a chance.

I would drill a small hole and use a bolt until you can find one actually two holes to keep it straight 

I did exactly what HT1kid explained.. I used a nut with the nylon bushing so it wouldn’t vibrate apart.. I did not tighten it to squash it, only to draw them together and stopped there.. it’s worked well so far, not that I put on many miles either..
Sneezles61

If you do a search there are plenty of solutions including a part number without the rubber that fits.  Also several pictures of how people have bolted it together with a small bolt and nut. 

Yamaha recycled a lot of parts...  a couple of my old bikes take the same part as a modern YZ85....  it's shorter but could be adapted to work with an extension bracket cobbled up.  I use the new Yamaha part but here is a cheaper one on ebay.

YZ85 rubber mount on ebay

I used 24 hour epoxy on mine. Still holding strong 5 years later.
Cheers

OEM part when available , is expensive . Someone relatively recently did a reproduction part .
I had a feeling it might have been KDI , but could be wrong . There is likely a link to KDI's website
on the Forum .

Here is a pair on eBay, very cheap price for quantity 2, at that price worth a shot to see if you can make them work.

 

I bought a reproduction piece for my DT2 last fall off eBay. Piece was an exact match. Seller was motodave and was part #308-1477. $26.50, free shipping.