These models were all released at the same time, and as such I'm going to assume that they all have the same basic chassis/mechanism. So, to save myself a bit of time (and money) I'm going to review them all here.
As is generally the case with brass, these models are all gorgeous. Unfortunately, they do lack window glazing, headlights, and couplers (also generally the case with brass, or so it seems). On the plus side, Micro-Trains friendly coupler pockets (and screws) are provided.
Reviewing the performance on these models is a bit tricky. The mechanism is very typical of 1980s Samhongsa design - featuring all-wheel pickup and propulsion, a 5-pole motor, and multi-piece plastic driveshafts. And no doubt these ran pretty well back in the day - good slow-speed creepability, reasonable top-end, smooth throttle response, no problems with narrow-radius curves, no problems on Code-55 rails, etc. Sure, maybe a bit louder than we'd like to see nowadays, but respectable. And yeah, the wheeltop wipers are distressingly primitive. (not to mention all that "problem waiting to happen" wiring running all over the place). But come on, we're talking 1984.
Unfortunately, these models have not aged well at all - this due to the plastic gears inside of the truck towers. Whatever plastic Samhongsa used way-back-then turns out to have been prone to shrinking and/or cracking. And the end-result (in the 21st century) is a lot of locomotives that spin their motors and driveshafts quite well, but with none of that motorized enthusiasm making it to the trucks. And beware - adding any sort of lubrication into the mix at this point will only makes things worse.
So, I suppose if you could time-travel back to 1984 and purchase one of these new, it might run at a "B" level. Unfortunately, based on my experiences they seem to be performing at "F" levels these days. Then again, replacement gears are an option (if you can find them), so I guess I'll split the difference and give them an overall "C" rating.
Notes and trivia-
The undecorated units came with ala-carte dynamic brake blisters.
To remove the shell, unscrew the two small screws (one on either side of the fuel tank). The shell should pull right off at that point.
Beware trying to work on the trucks. Yeah, the gears are all easy enough to get at - just remove the three screws from the bottom of a given truck. Unfortunately, this will cause the entire assembly to fall apart into a million different pieces. And just try to get everything put back together correctly - it takes more hands than human beings were born with!
Be very careful with the screw that connects the two halves of the truck towers (and runs through the dreaded plastic gear). The threaded end is awfully short and prone to stripping.
If you're looking for replacement gears, NWSL may be able to hook you up. I replaced the cracked plastic gears in my GP18 with their "1074-6 23 Tooth" gears and was able to get it running again.
High-nose versions were also part of this same release:
Grade: C (and I guess "B" with the worm tower gears replaced)