Thanks for the replies. They did come with my Lobaugh J&L tank car kit. The package had been opened and marked in ink "No 3 SP cab". I penciled in "Lobaugh?" because I didn't know. I thought them too crude to use for the kit and did not use them. The bolsters weren't changed, so they could be mounted if the car ever finds its way to a purist. I'll keep them in the box; they'll go with the car when it goes.
I appreciate the willingness of all of you to share your knowledge.