Evaporative emissions dilemma

I've been chasing an evaporative emissions code for years... 2 codes, large and small. Had the "dealer" do a smoke test only to be told I did not have a leak and they couldn't hazard a guess as to why I got the code... 2 years later I take the vehicle to a local small shop with smoke test machinery. Tons of smoke exiting somewhere high above the gas tank. GREAT !!! It's a hose!!! No it's not. According to the technician it's a "Spider" that has about 4 hoses running into it. Accessible by taking off the right rear wheel and an access cover. Says the part will cost $350. I cannont find this part on a diagram... Anyone know what this part is on my 2002 Grand Cherokee 4.7 litre? Thanks!

 

Could you get a look at just what this part looks like? Like with a flashlight inside a wheel well or nearby location? It could be possible to develop your own "Spider" with purchased parts from an auto parts store. The gas tank comes out easy enough after pumping out gas from the tank. You can get a hand pump from an auto or hardware store. Find a way to store the gas. Its a lot of work but compare that with the total labor and dealer parts that it will cost you.