Without pictures or more details its hard to ID a Dan Wesson as there were lots of models.
Try here:
http://www.danwessonforum.com/forum
For better info as that site specializes in Dan Wessons & has a handy "What model do I have" helper you mighgt find useful.
Many, but not all DWs were interchangable barel guns so you might want to check if either the barrel was incorrectly reassembled, or the 8" is the original barrel.