The new dorman hose setup had a larger diameter hose on the lower leg going to the rear heater core, but the upper and the front was the same size as the original. I couldn't reuse the old hose on the metal dorman tee, dorman made the new tee with two large nipples and one small nipple, a total opposite of the factory tee. The factory tee had a large nipple on the front that goes back to the engine and the top nipple that goes to the heater control valve was smaller, and the nipple that goes to the rear heater was small. But the dorman tee has a large nipple on the front and rear and only the top one is small. So anyway, since I had to use the complete dorman setup, I made a few revisions. Down underneath where the tubes are for the rear heater the tube has a small hose barb to keep the hose in place and larger barb used as a hose stop, but the dorman hose would slip right past the large stop barb, so I triple clamped the lower hose. I slid the hose on past the large stop barb and put one clamp in front where the clamp should go, and two more after the large stop barb. Apparently it worked because I used a vacuum fill tool and pulled the entire cooling system down to 26" of vacuum, closed it off and walked away for 3 hours. When I returned it was still at 26" so if it holds that for 3 hours, it should not leak. Only time will tell. I also put a heat shield sleeve over the whole lower hose section and over part of the front hose where its next to the exhaust.