Wow, since the thread is back to life I discover a bunch of questions that went unanswered
The abdomen wrap was (at the time) known as Swanandaze, I believe it has went extinct. The larva lace on the other patterns looks to be the same thing. The color can be altered by changing the wrap to rust red or gray and using a marking pen on the moose mane. You can make these out of dyed buck tail also and it sinks better.
As for weighting them, I did this with many and it did get them down but due to all the rocks and rubble on the creek & river bottoms many were lost because of the weight. If you decide to use lead wire under the body don't get carried away or they will get snagged often. They are too hard to tie for you to just go out and lose them. I found that unweighted and used with a lead head leader they worked well dead drifted and then allowed to swing.
To fine the tying instructions type the words 'Moose Mane Crayfish' into your search engine. The last time I looked the web link was still there with a history of the fly and the man who created this very realistic pattern.
Glad you fellas liked that