Bicycle Mechanics - swapping derailleur cages

I have an ultegra derailleur 6500 with a bent cage. The body and springs are still in good condition. I saw a park tools guide to disassembling derailleurs and the model they used had a hex screw mounting the cage to the body. On mine it looks as it is rivited or the bolt is on the inside. Is there any way to remove the cage on this derailleur. I want to put a long cage on it to run it on my mtb. Thanks.

Limitation is :

I can't look over your shoulder and see what you are talking about, online, in text..

Do you have a place to sell you just the cage? or are you cannibalizing a broken derailleur?

I have done that with an 80's Campag Olympus. [Back when they were dabbling in the MTB sector]
but they are better, with spare parts than Shimano..

I'd just get a new RD.

293098

The piece I am talking about is the bolt or shaft in the top right portion of the cage. It is where the cage meets the derailleur body. I have the pieces I need I just dont know if there is a way to remove this from the body. I hope this clarifies.

Any other input is greatly appreciated. Thanks.

You should be about to remove th C clip from the mounting bolt . and the cage will come off . Here check this out , http://www.parktool.com/blog/repair-help/rear-derailleur-overhaul

What size cassettes? A road derailleur cannot handle some of the larger cogs found on most mountain cassettes. A longer cage will not change that.
You need a 9-speed mountain type derailleur.

I did it, it was the P-screw that I was overlooking. I ended up putting a long cage from an old stx derailleur on the ultegra body, I used the ultegra spring as well as it worked with the tension. Im satisfied as this saves me from having to buy a new one for now. Thanks for the link.