Re: Slide Rail Extension
Yes, you are correct that the interior distance is 1/4" narrower with the extensions.
When you do your trimming, and having 3 bogey wheels, make SURE that you remove 1/8" from each side of the center wheel. If you only remove the 1/4" from one side, the center wheel won't line up properly with where it needs to be in the track. (Yes, this is from experience!)
I used a pipe cutter on the aluminum tube for one side, and a grinder for the black plastic spacer on the other side.
The axle remains the standard length.
Enjoy your 141---it's well worth the investment.