The HT23 has a heaver bolster then the rest of the large frames.
I hate to say this Jerome but that info is incorrect.
The 1886 thru the first run Ht23 with a serial number 01 used the same front axle, pivot pin and bolster. The HT23 that starts with a serial number 02 and up had a bigger pivot pin so the hole thru the axle and bolster needed to be bigger. I have heard of a heavy duty bolster but yet to ever see one that is any different then the rest other then the pivot pin area.
There may be some confusion between the bolsters but I think there was a material change to make them harder which is why they did not use pivot pin bushings in the later ones. But this is a guess from me on that.