I don't know if anyone sell individual parts but if anyone does I'd say it would be DJM.
Anyhow....components are as follows:
1> c-notch (which you have) with bolts
2> 4 longer u-bolts with bracket aka U-bolt kit
3> 2 axle saddles
4> 2 shock extenders
5> possibly 2 leaf pack bolts (some people need to remove leaf springs from the pack like I did)
I think thats about it. It's early...I may have forgetten something but someone will double check it for me