Yeah Elwyn; I do not know what the difference is between the 23 and 24, but he did have a large poster with all the specks on it, and it did say PT 23. Boy, there were some great sounding old radials there. I did not get a picture of it, but there was an old Meyers bipe with a 5 cyl. Kinner engine also. Those things sound like they are idling when they take off. Just do not turn up very many rpm's.