[Richard]

This has been cussed and discussed before, but since I had an opportunity to fit a new hose to the Dupree attachment today, I thought I would post the easy solution. 

For those who have done this or attempted this, you already know the male section of the Dupree attachment is larger than the ID of the sewer hose. The wire inside the sewer hose prevents you from easily stretching the hose to slip over the larger OD. 

Locate a tapered glass or sturdy cup that the small end fits in the hose, but the large end is larger than the hose. Slip the sewer hose over the cup, and heat with a hair dryer. When the plastic is warm, you can slide it down a bit. Reheat and repeat until the hose will fit over the Dupree fitting. I use a standard radiator clamp to secure.