I have a Bachamn  made, N&W  black hopper car, with numbers : N&W12988 .
It has Kdee couplers.
it needs some axles, I am thinking of using metal axles and wheel type,.
But I don't know if it  needs  33"  or 36" and can't find  info to tell me for sure
I do not have the original box, I bought it used.

Can any one help by telling me which?

Hi, I have a used  bachman  heavy duty  / heavy load hauling flat car.
it reads on the side: Louisville and Nashville 24562
it has 4 trucks. and a red plastic frame.
The present wheels and axles are plastic.
It rolls pretty well except that both trucks closest to the middle of the car, frequently derail when  crossing a switch or crossing, or it the car is placed any where in the train other than  very close to the end of the train.  and I want to correct that.
I have replaced the axles and wheels of the inside trucks with new plastic types but still little improvement.
I also glued metal BBs to the underside for added weight, which I think helped some as the derailments are not as frequent after doing so......,
and I don't think I should add still more weight?...as the car now weighs 4 oz.
can i safely add more weight?..but how much more?
So I am thinking of installing metal wheels and axles on the two inside trucks,  in hopes that will help or correct the problem,
but I don't know and can't find  info to tell me for sure if  this car needs 33" or 36" wheels, or just what size.?
Can any one help by telling me which?
and I welcome your suggestions and cures for the derailing issue.