Installed a heatercraft in my A22 and here's some of the pics if it will help anyone else out. Was more time consuming as I didn't know where to start and made it up as I went along.
First thing to do is pull out the cover under the dash and move the lines if needed. I then placed the heater where I thought it would work and put the cover back in place and looked through the cup holder to see if all was well.
Next pull up the cover over the gas tank and use some adel clamps to keep the hoses up, not sure if this is needed. Found some extra ones up under the dash. The hoses will slip up under the hull and floor pretty easy.
Don't have a pic of the Y-tube but I placed it on the port side of transmission in the tube leading from the tranny to the water pump. Hope that's the right place. Used garden hose fittings as they were cheap and they'll be easy to blow out.
Next is to try and figure out where to put the tubes. I opted for under the dead space behind the chilax seat. Was going to put them in the walk way but wanted to save that space for future speakers since I'm not a fan of tower speakers. Put the smaller vents up under the dash.
Tubes reach the back seat no problem, they don't quite make it to the front. Might want to rethink putting one in the walk way.
Hope this helps.