Can I switch the couplers on prewar cars to knuckle couplers? I have green metal passenger cars that I thought were all prewar because they looked the same, but upon inspection, some are "hook" couplers and others are knuckle couplers. I have two steam locomotives, a 224E prewar with a tender (not sure if it's correct tender) with a rear "hook" coupler. I have a 1666 from 45 or 46 with a tender (again, not sure if it's the correct tender) with a rear knuckle coupler. I have quite a few prewar freight cars with two different types of "hook" couplers. If possible, I would like to convert all the "hook" couplers to knuckle couplers. If it's possible, what knuckle couplers should I look for? Do I have to also change out the wheel trucks?
I thought I posted a similar query earlier, but I cannot find it now.
I've attached a photo of the prewar green metal passenger car with "hook" couplers. I also have 3 passenger cars that look pretty much the same as this one, but they have knuckle couplers.