Take a look at the pics in the Sacramento Craigslist ad.
The Long rams were used from '59 - '62. They can be distinguished by the tube divider line running the length of the siamesed tubes from the carb plenum to the head mounting surface. (Look at the unpainted set of tubes in the ad photos.) These earlier versions used a log type exhaust manifold with a single exhaust heat riser tube on each side from the manifold to the bottom of the carb plenum to keep the fuel atomized in cooler temps.
The turquiose painted rams are the Short version, used only in '63-'64, paired with the cast iron headers shown just above them. Notice the tube divider line only runs from the head mounting surface to about the mid point of the the length of the runners. The reason was to effectively increase the carb plenum volume in order to raise the torque peak higher up the RPM's. This version also used two heat tubes on each side, the forward, shorter tube is to feed the exhaust heat under the floor of the plenum, and the second, longer, aft tube is to evacuate the exhaust.
Exhaust corrosion and burn through the bottom of the carb plenum and thermostat well was a common problem with these intakes. The heat riser tubes also served a secondary purpose of supporting the cantilevered weight of the intake and carb. Note also there is a balance tube connecting the l/h and r/h plenums. That the thermostat wells exist on these intakes is kinda of odd, as this set-up only was ever equipped with a dual cable manual choke.
Incidentally, their use was not only on the 413. They were available in Dodge, Plymouth and Desoto also. And were available as a package on every displacement starting with the 361.
While these engines were absolute torque monsters, they petered out at pretty low RPMs with these intakes. The later, Short version would run to higher HP levels at higher revs with slightly diminished torque. But they were designed to move heavy weight luxury cars down the turnpike at high speeds.
Many years ago, I purchased an original ram powered '64 300K letter car coupe. I had it stored behind my rental house in KY. I had taken a job out of state and was commuting on a weekly basis. About a year into the job, I needed to relocate permanently. Toward the end of the move, I came home one time and the car was missing. For reasons unknown today, I had stored the bumpers, intakes and exhaust manifolds in the basement. Unfortunately, all the rest of the piece parts, carbs, linkage, air hats, etc, were still in the trunk. I reported it to the pokice and spent days canvassing every scrap yard in 30 miles. The car never surfaced again. I can only figure scrappers or racers took it.
(On a funny note, a young friend of mine was using a '62 or '63 Imperial as a daily driver. He must have been stopped at least two dozen times because of the stolen car report! LOL)
Fortunately, if you have the intakes and exhaust, nearly everything else except the air hats are reproduced... Not cheap, but available. My set WILL end up installed in my '64 300 'vert. I've owned it for 37-38 years, and am slowly putting it back together 35-36 years AFTER I took it apart.
Mike in FL