If indeed you have DD-3's and want to switch to spring brake cans, I've done it and it's pretty simple, huh Clifford!
It's a great modification, DD-3's are expensive to rebuild/buy, that is if you can find them. They quit making them last year. Spring Brake cans are easy to find and cheap, 35-50 Bucks each for the 30/30.
A couple of links to get you excited!
viewtopic.php?f=5&t=113
viewtopic.php?f=9&t=14&start=20
