Todd,
The passenger side is one piece while the driver's side has the #7 tube seperate to install over the frame rail. You also don't need a 90* oil filter adapter if using a short filter and they have good plug wire clearance. The driver's side was a little more difficult than the pass. side, but having the starter removed and engine pulled up off of the mounts is the way to do it. It's been a few years since I installed them with the engine in and it did involve a lot of engine wiggling and steering movement, but I believe I did it without removing the center link. But it was also on an open-center trailer with the engine jacked up. TTI instructions may call for link removal which would make it easier.
Some people have clearance issues, but that is usually the result of tweaked frames or worn engine or trans mounts that cause everything to settle. Just in case, a small bit of adjustment can be made in the mounts through shims on the '72 & older style or the engine can be shifted a bit with the later spool-type mounts. I like the poly mounts over rubber.
Plenty of oil pan clearance as well, even with the 8qt. Milodon that has the flared out sump. But obviously that wouldn't be an issue in Pure Stock.
www.ttiexhaust.com