"Rascal" The 1976 Plymouth Feather Duster
The easiest way to pull the later bumper in would be to make a new set of bumper brackets. I know, doesn't sound easy, but I think you'll find messing with the shock mounts is a real pain.
The other thing to consider is that the bumper is wider than the back end of the car. Sucking it into the car will not give the same clean look as the earlier bumpers because the bumper will still stick out past the quarters, and if you pull it in you'll have to figure out a new way to fill in the gap. It will be a smaller gap, and the stock filler won't fit.
The easiest thing to do would be to get ahold of a 70-73 bumper and brackets and ditch the shock mount bumper entirely. Even with the aluminum bracing I bet the earlier bumpers are still a weight savings, they're about 50lbs lighter than the steel shock mount version. Mounting the early bumper is pretty easy. The reinforcing panel for the bumper, even on the later cars, still has a hole for the outer bumper bracket mount, you just have to drill it through the lower tail panel. But the hole is there on the backside. The problem is that the inner bumper bracket mount hole falls right in the middle of where the shock mount passes through the lower tail panel. So, you have 2 options- 1. weld a plate into the lower panel and drill a hole for the mount or 2. make a bracket to bolt to the frame and bumper bracket. That's what I did on my car, but I'll probably just weld it up the next time I have my bumper off. I have the entire write up in my build thread on page 3, scroll down to post 70.
http://www.forabodiesonly.com/mopar/showthread.php?t=198098&page=3
Before
During
After
The easiest way to pull the later bumper in would be to make a new set of bumper brackets. I know, doesn't sound easy, but I think you'll find messing with the shock mounts is a real pain.
The other thing to consider is that the bumper is wider than the back end of the car. Sucking it into the car will not give the same clean look as the earlier bumpers because the bumper will still stick out past the quarters, and if you pull it in you'll have to figure out a new way to fill in the gap. It will be a smaller gap, and the stock filler won't fit.
The easiest thing to do would be to get ahold of a 70-73 bumper and brackets and ditch the shock mount bumper entirely. Even with the aluminum bracing I bet the earlier bumpers are still a weight savings, they're about 50lbs lighter than the steel shock mount version. Mounting the early bumper is pretty easy. The reinforcing panel for the bumper, even on the later cars, still has a hole for the outer bumper bracket mount, you just have to drill it through the lower tail panel. But the hole is there on the backside. The problem is that the inner bumper bracket mount hole falls right in the middle of where the shock mount passes through the lower tail panel. So, you have 2 options- 1. weld a plate into the lower panel and drill a hole for the mount or 2. make a bracket to bolt to the frame and bumper bracket. That's what I did on my car, but I'll probably just weld it up the next time I have my bumper off. I have the entire write up in my build thread on page 3, scroll down to post 70.
http://www.forabodiesonly.com/mopar/showthread.php?t=198098&page=3
Before
During
After
