Here is the cable that some have said they used.  hvccycle.net/yamaha-dt250-dt360-dt400-th...-cable-437-26311-02/

And again, the elbow that clips into the carb top is a separate part...   and shouldn't be too hard to find if yours is missing.  

This is the elbow referred to.

Some sellers charge a lot, but it can be acquired cheap if, say, bought with a RD carbs parts lot.

TUBE, WIRE GUIDE for DT360 1974 USA - order at CMSNL

any idea where one could find that fitting?

I just googled & found that HVC cycle cable set & thought I was realy onto something but I'm late to the party haha
looks good though for $65. Less the carb elbow I guess.

Now that I think about it wouldn't the elbow affect the cable length?

Cable length take the elbow into account & allows for it in length. Correct elbow is threaded t the top end for the adjuster to thread onto. Proper elbow may not have the locknut without looking, so might need to adjust the slack out of bottom cable & tape it to get it to stay there. Something like that. I think the correct cable set could have the boot cover part with a long top to cover right up past the adjuster. Part pic should show it i that's the case.

Now that I think about it wouldn't the elbow affect the cable length?

The original DT360 cable is designed for the elbow so the inner cable is the correct length with elbow installed.

Someone may have tried to use a different cable from another model, an incorrect aftermarket part, or who knows what happened on your bike?

I just ordered a new set of throttle cables and a elbow from HVC Cycles. Thanks for your responses.

I just got my new throttle cable from HVCcycle.My problem is the carb end is straight. I need a 45degee adapter. I had a custom cable made for the lower throttle cable with the 45 on the end.My hope is to take the splitter apart and swap out the cable with the custom one. Confused yet? I am. Now I need a fitting to fit into the top of the carb for the cable to fit in. Any idea where I could find something like that? thanks  the straight cable hits the frame. 

I found the piece I need at CMSL. My luck out of stock.