Hmm, so you refused them because the springs fell off? The springs fall off easily when they're rubbing against the inside of the envelope. They're easy enough to put back on.I went & picked up my bulk #148's this morning - they were loaded with loose springs - I refused them and drove 80 miles to a different LHS that had two bulk packs 50 pairs of #5 which I bought - now I am set for a long time.
MDC trucks need a LOT of shimming to get to the correct height.I end up replacing trucks on MDC and Athearn with new trucks from Athearn (as long as they have the metal axles) or from Accurail or Walthers and use Intermountain wheelsets.
I've found using #5 Kadees necessary for Athearn Blue Box kits because the whiskers of #14s will poke out around the sides of the metal coupler cover and the underframe and get stuck.
I have started looking at more prototypes and found that many bulkhead flats, some 100 ton boxcars, and others use a longer shank coupler than what the #5 and #14 are.
If installed correctly, the Blue Box snap-on coupler pocket lids should not be drooping or allow any space for the whiskers to get caught. If there is a gap for the whiskers to get caught on, then the cover is not in all the way.
The longer shank is compensated for by the larger coupler head. Atlas bulkhead flats for example, have a shorter coupler pocket so that a medium shank Kadee would fit and have the correct coupling distance. You'll see what I mean if you use the #58 scale head Kadee couplers. The 100-ton box cars should have a cushion coupler pocket which sticks out from the end of the car. Atlas and Athearn RTR cars have the pockets with the mounting post further out to compensate for this and to create a prototypical coupling distance.